English Grammar: Sentence Transformation and Completion

The correct prepositional usage is 'useful for' someone and 'take part in' an activity.

The sentence requires a noun to follow 'period of'. 'Preparation' is the noun form.

When converting 'Very few things are as useful as television' to a superlative, it becomes 'Television is one of the most useful things'.

The original sentence uses the present tense, so the compound version must maintain that tense. Option C correctly uses 'watch' and 'spend' to match the original structure.

The original sentence establishes a positive condition. Option C correctly uses the prepositional phrase 'By watching' to maintain the meaning that television facilitates learning.

In passive voice, the verb 'telecast' remains 'telecast' in its past participle form. Option D correctly follows the structure 'should be + past participle'.

The relative clause requires the correct subject-verb agreement. 'Programs' is plural, so 'are' is required, and 'telecast' is the correct past participle form.

To form an interrogative from a positive statement, use the auxiliary verb 'do' in the negative form. 'People' is plural, so 'Don't' is the correct choice.

To transform a positive statement into a negative one while keeping the meaning, use a double negative construction. 'There is no family without a television set' effectively means every family has one.

A complex sentence requires a dependent clause. Using 'so that' with the past tense 'could' correctly explains the purpose of the scientists' hard work.

The active voice requires the subject to perform the action. 'Scientist did not invent it' is the correct active form of the passive 'It was not invented'.

When transforming a superlative to a positive degree, 'one of the' requires 'Very few... are as... as'. This maintains the plural subject agreement.

The structure 'so... that' indicates a result. Since the boy is weak, the result is that he cannot solve the problem.

This is a common proverb. The completion 'divided we fall' correctly contrasts with 'united we stand'.

'I wish' is the standard phrase used to express a desire for something that is not currently true or possible.

In this relative clause, 'whom' is the object of the preposition 'for'. Therefore, 'whom I was looking for' is grammatically correct.

This is a conditional sentence (Type 1). The 'if' clause is in the present tense, so the main clause should use the future tense.

The sentence requires an adjective that completes the meaning of an honest man's behavior toward others. 'Responsible' is the most logical choice.

An honest man is not 'harmful' to anybody. This fits the context of honesty and moral character.

The antonym of 'honesty' is 'dishonesty'.

Sentences starting with 'Let's' (Let us) always take 'shall we?' as the tag question.

The statement 'Nothing is more pleasant' is negative in meaning, so the tag question must be positive. 'Is it?' is the correct tag.

The subject 'memories' is plural, and the sentence is positive, so the tag must be negative and plural: 'Aren't they?'.

The word 'hardly' makes the sentence negative in meaning. Therefore, the tag question must be positive. 'Do we?' is the correct form.

When the subject is 'everyone', the tag question uses the pronoun 'they'. Since the sentence is positive, the tag is 'aren't they?'.