B – part. The word has to collocate with ‘life’. While all four words convey the same idea, only ‘part’ works well in this context.
D – keep. This sentence expresses the idea of staying entertained at a certain period of time (‘when we have nothing to do’), so the word ‘keep’ works best. ‘Have’ does not work here as it expresses the idea of somebody else doing something for you (‘I have my car washed twice a week’ – I do not do it myself).’Make’ and ‘allow do not collocate with ‘entertain’.
C – turn. Preposition ‘into’ helps us to make the right choice – ‘switch’ and ‘move’ would normally take ‘to’ in this context. ‘Become’ requires no preposition.
B – wrong. Another strong collocation – ‘to go wrong’. ‘To go bad’ means ‘to expire’ and is normally used to talk about food past its expiration date.
C – hand in hand. If two things go hand in hand, they are closely connected or dependent on one another. If something costs ‘an arm and a leg’, it is extremely expensive. Meanings of answers B and D should be clear.
A – convinced. The idea of the sentence is that a certain group of people has particular beliefs. ‘To be convinced of/about something’ is the phrase that most closely conveys this idea. ‘Some people are believed’ has a completely different meaning, indicating others having a certain belief of opinion about these people.
B – encourage. To make someone do something, to promote or welcome such action or behaviour.’Enforce’ means to introduce something forcibly, usually by means of law.
D – express. Concern can’t be said, told or pronounced. The only correct collocation from this list is ‘to express concern’