The correct answer is "happiness". The noun form of the adjective happy is happiness, changing y to i and adding ness.

The correct answer is "dangerous". The adjective form of the noun danger is dangerous, adding ous.

The correct answer is "modernize". The verb form of the adjective modern is modernize, meaning to make modern.

The correct answer is "decision". The noun form of the verb decide is decision, changing de to sion.

The correct answer is "comfortable". The adjective form of the noun comfort is comfortable, adding able.

The correct answer is "strength". The noun form of the adjective strong is strength, a vowel change from o to e.

The correct answer is "careful". The adjective form of the noun care is careful, meaning full of care.

The correct answer is "simplify". The verb form of the adjective simple is simplify, meaning to make simple.

The correct answer is "creation". The noun form of the verb create is creation, removing e and adding ion.

The correct answer is "successful". The adjective form of the noun success is successful, adding ful.

The correct answer is "information". The noun form of the verb inform is information, adding ation.

The correct answer is "beautify". The verb form of the noun beauty is beautify, changing y to i and adding fy.

The correct answer is "harmless". Harmless means causing no harm, while dangerous means full of danger. The question asks for an adjective with negative meaning, but harmless has a positive connotation of safety. However, harmless is the opposite of dangerous. The intended correct answer here is harmless as it is the negative form of dangerous meaning not dangerous.

The correct answer is "possibility". The noun form of the adjective possible is possibility, changing ble to bility.

The correct answer is "shorten". The verb form of the adjective short is shorten, meaning to make shorter.

The correct answer is "useful". The adjective form of the noun use is useful, adding ful.

The correct answer is "development". The noun form of the verb develop is development, adding ment.

The correct answer is "powerful". The adjective form of the noun power is powerful, adding ful.

The correct answer is "activity". The noun form of the adjective active is activity, changing ive to ivity.

The correct answer is "widen". The verb form of the adjective wide is widen, meaning to make wider.

The correct answer is "make". The natural collocation is make a decision, meaning to choose between options.

The correct answer is "pay". The natural collocation is pay attention, meaning to focus or listen carefully.

The correct answer is "full". The natural collocation is take full responsibility, meaning to accept complete accountability.

The correct answer is "promise". The natural collocation is break a promise, meaning to fail to do what one promised.

The correct answer is "your". The natural collocation is do your homework, meaning to complete assigned schoolwork.

The correct answer is "good". The natural collocation is make good progress, meaning to advance or improve significantly.

The correct answer is "cold". The natural collocation is catch a cold, meaning to become ill with a common viral infection.

The correct answer is "some". The natural collocation is have some fun, meaning to enjoy oneself.

The correct answer is "break". The natural collocation is take a break, meaning to pause and rest from an activity.

The correct answer is "some". The natural collocation is give some advice, meaning to offer recommendations or guidance.

The correct answer is "mistake". The natural collocation is make a mistake, meaning to do something incorrectly.

The correct answer is "some". The natural collocation is do some exercise, meaning to engage in physical activity.

The correct answer is "look". The natural collocation is have a look, meaning to glance or examine briefly.

The correct answer is "notes". The natural collocation is take notes, meaning to write down key information.

The correct answer is "effort". The natural collocation is make an effort, meaning to try hard.

The correct answer is "on". The natural collocation is catch on fire, meaning to begin burning.

The correct answer is "business". The natural collocation is do business, meaning to engage in commercial activities.

The correct answer is "speech". The natural collocation is give a speech, meaning to address an audience formally.

The correct answer is "plan". The natural collocation is make a plan, meaning to prepare a course of action.

The correct answer is "action". The natural collocation is take action, meaning to do something to achieve a goal.

The correct answer is "would have". This is an inverted third conditional sentence. Had I known means If I had known, then I would have attended.

The correct answer is "had". Inversion with no sooner requires the past perfect and subject-verb inversion. No sooner had he arrived than it started raining.

The correct answer is "was". Inversion with not only requires the auxiliary verb before the subject. Not only was he late, but he also forgot his notes.

The correct answer is "have I seen". Inversion with rarely at the beginning requires the auxiliary have before the subject I.

The correct answer is "that". The structure It was not until that emphasizes the time when something happened.

The correct answer is "was". Inversion with so difficult requires the verb to be before the subject. So difficult was the exam that...

The correct answer is "did". Inversion with only after requires the auxiliary did before the subject she.

The correct answer is "had". Inversion with hardly requires the past perfect. Hardly had I arrived when the phone rang.

The correct answer is "did". Inversion with not until requires the auxiliary did before the subject he.

The correct answer is "did". Inversion with little at the beginning requires the auxiliary did before the subject they.

The correct answer is "would have". This is an inverted third conditional sentence. Had she studied harder means If she had studied harder, then she would have passed.

The correct answer is "have". Inversion with never requires the auxiliary have before the subject I.

The correct answer is "did". Inversion with so quickly requires the auxiliary did before the subject time.

The correct answer is "did". Inversion with only then requires the auxiliary did before the subject we.

The correct answer is "would have". This is an inverted third conditional sentence. Had it not been means If it had not been, then I would have failed.

The correct answer is "had". Inversion with scarcely requires the past perfect. Scarcely had the meeting started when the fire alarm rang.

The correct answer is "is". Inversion with not only requires the verb to be before the subject. Not only is she talented, but she is also hardworking.

The correct answer is "can". Inversion with only by requires the modal can before the subject you.

The correct answer is "did". Inversion with at no time requires the auxiliary did before the subject he.

The correct answer is "should". Inversion with under no circumstances requires the modal should before the subject this door.

The correct answer is "old enough". The structure too young to drive is transformed to not old enough to drive, where enough comes after the adjective.

The correct answer is "seen". The present perfect tense requires the past participle seen after have not. I haven't seen him for two years.

The correct answer is "to". The verb promised is followed by an infinitive with to. She promised to help me.

The correct answer is "might". Might have forgotten expresses possibility or uncertainty about a past action.

The correct answer is "was built". The active voice built becomes passive voice was built in the past simple tense.

The correct answer is "has worked". The phrase since 2015 requires the present perfect tense has worked.

The correct answer is "not to". The negative infinitive is formed with not to. He told me not to touch that.

The correct answer is "don't have to". Don't have to expresses lack of necessity, while mustn't expresses prohibition.

The correct answer is "is better". The comparative form better is used to compare him to other players. No one is better than him.

The correct answer is "drink". After would rather, the base form of the verb is used. I would rather drink tea than coffee.

The correct answer is "too". The structure is too plus adjective plus infinitive to express excess. The exam was too difficult for me to pass.

The correct answer is "hadn't been". This is a third conditional sentence. If she hadn't been ill, she would have gone to the party.

The correct answer is "was". In reported speech, the present tense are changes to past tense was.

The correct answer is "eaten". The present perfect tense requires the past participle eaten after have not.

The correct answer is "mustn't". Can't expresses impossibility, and mustn't can also express strong deduction that something is impossible.

The correct answer is "is said". The passive construction is said to be used to report what people say. He is said to be rich.

The correct answer is "too". The structure too plus adjective plus infinitive expresses excess. She was too tired to stay awake.

The correct answer is "had". After I wish, the past simple tense is used to express a wish about the present. I wish I had more money.

The correct answer is "were". In second conditional sentences with if I you, were is used for all persons. If I were you, I would study more.

The correct answer is "able to". Wasn't able to is the negative past form of can, expressing inability.

The correct answer is "had". This is a second conditional sentence about an unreal present situation. If I had more time now, then I would learn another language.

The correct answer is "has lived". The phrase since 2010 requires the present perfect tense has lived to indicate an action that started in the past and continues to the present.

The correct answer is "had started". The past perfect tense is used for an action that was completed before another past action by the time we arrived.

The correct answer is "going". The verb suggested is followed by a gerund the ing form. He suggested going to the cinema.

The correct answer is "were". After I wish, the subjunctive mood uses were for all persons when expressing an unreal wish.

The correct answer is "was he". Inversion is used with not only at the beginning of a sentence. Not only was he late, but also...

The correct answer is "waking up". The phrase get used to is followed by a gerund the ing form. She can't get used to waking up early.

The correct answer is "had studied". This is a third conditional sentence: if plus past perfect had studied, then would have passed.

The correct answer is "told". After I'd rather you, the past tense told is used to express a preference about someone else action.

The correct answer is "had I arrived". Inversion with hardly requires the past perfect and subject-verb inversion. Hardly had I arrived when...

The correct answer is "taking". The verb denied is followed by a gerund the ing form. She denied taking the money.

The correct answer is "had we left". Inversion with no sooner requires the past perfect and subject-verb inversion. No sooner had we left than...

The correct answer is "working". The phrase is used to is followed by a gerund. He is used to working long hours means he is accustomed to it.

The correct answer is "saying". The verb regret can be followed by a gerund to refer to a past action that you wish had not happened.

The correct answer is "will have been completed". By next month refers to a future time, so the future perfect passive is required.

The correct answer is "did". The phrase It's high time is followed by the past simple tense to express that something should be done now.

The correct answer is "would have left". This is an inverted third conditional sentence. Had I known means If I had known, then would have left.