5. Choose the most appropriate words to complete the sentences and underline them.
1. Jane, dear, you (ought not/must not) to work so
hard: you look a bit tired.
2. Dad (should/has to) get up early on weekdays, but at
weekends he can sleep longer.
3. Don't you think that you (have to/ought to) thank
Mary for her wonderful present?
4. This (should/must) be John's favourite programme
he watches it every Saturday.
5. Last Monday we (should/had to) write a very diffi-
cult test.
6. You (don't have to/mustn't) be rude talking to Ann.
It's the last time I'm warning you.
7. All people (ought to/have to) get some knowledge of
geography, (oughtn't/don't) they?
8. It (must/has to) be raining: I can hear raindrops
beating on the roof.​

1. Jane, dear, you ought not to work so hard: you look a bit tired.
In this sentence, the appropriate word to complete the sentence is "ought not." This is because the phrase "ought not" expresses advice or a suggestion. In this case, it suggests that Jane should not work so hard because she looks tired.

2. Dad should get up early on weekdays, but at weekends he can sleep longer.
In this sentence, the appropriate word to complete the sentence is "should." This is because "should" is used to express a recommendation or an ideal situation. In this case, it is recommended or ideal for Dad to get up early on weekdays.

3. Don't you think that you ought to thank Mary for her wonderful present?
In this sentence, the appropriate words to complete the sentence are "ought to." This is because "ought to" expresses obligation or duty. In this case, it is suggested that the person should feel obliged to thank Mary for her wonderful present.

4. This must be John's favourite programme; he watches it every Saturday.
In this sentence, the appropriate word to complete the sentence is "must." This is because "must" is used to express a strong belief or deduction. In this case, the person strongly believes that the programme is John's favorite because he watches it every Saturday.

5. Last Monday we had to write a very difficult test.
In this sentence, the appropriate words to complete the sentence are "had to." This is because "had to" expresses an obligation or necessity in the past. In this case, the person had an obligation or necessity to write a very difficult test last Monday.

6. You mustn't be rude talking to Ann. It's the last time I'm warning you.
In this sentence, the appropriate word to complete the sentence is "mustn't." This is because "mustn't" expresses prohibition or a strong recommendation against doing something. In this case, the person is strongly advised or prohibited from being rude when talking to Ann.

7. All people ought to get some knowledge of geography, oughtn't they?
In this sentence, the appropriate words to complete the sentence are "ought to" and "oughtn't." "Ought to" expresses obligation or duty, while "oughtn't" is a contraction of "ought not." In this case, it is suggested that all people have an obligation or duty to acquire some knowledge of geography.

8. It has to be raining: I can hear raindrops beating on the roof.
In this sentence, the appropriate word to complete the sentence is "has to." This is because "has to" expresses a necessity or strong requirement. In this case, it is believed or deduced that it is necessary or required for it to be raining because the person can hear raindrops beating on the roof.