Must to express inference or probability

Must can be used with be to make an inference.

• She must be over forty. (= I suppose she is over forty.)
• He must be the oldest man in the village. (= I suppose he is the oldest man in the village.)
• He must be mad to do this. (= I think he is mad to do this.)
• He must be a fool to behave like that.

Exercise: Rewrite the following sentences using must.

1. I think he is joking.

2. I suppose he is mistaken.

3. Surely he is a stupid to behave like that.

4. I think the poor boy was punished by his master.

5. I think she is older than her husband.

Answers

1. He must be joking.

2. He must be mistaken.

3. He must be a stupid to behave like that.

4. The poor boy must have been punished by his master.

5. She must be older than her husband.

Can be + adjective

This structure can be used to talk about peculiar characteristics of people or things.

Read the following sentence.

• He is not always very annoying, but sometimes he is.

We can express the same idea using can be.

• He can be very annoying at times.
• She is not always very rude, but sometimes she is.
• She can be very rude.
• She is not always very dogmatic, but sometimes she is.
• She can be very dogmatic.

Exercise

Rewrite the following sentences using can be.

1. Raj is not always generous, but sometimes he is.

2. My Dad is not always stern, but sometimes he is.

3. It is sometimes very hot here in October.

Answers

1. Raj can be generous at times.

2. My Dad can be very stern at times.

3. It can be very hot here in October.