May be, might be and must be are all basically the same, and you use them when you want to say that you think something is true.
Suppose you have a boss, but you don’t know how old she is. You think she is around 45, but she could also be 41, or 47.
So you could say:
She may be in her 40s.
She might be around 45.
She must be at least 40.
May, might, and must can be changed around in these examples. So you could also say: She must be in her 40s. (or: forties).
When you say “must” it means you are a little bit more certain about it than if you say “may” or “might.”
Suppose you’ve been asleep at night, but after some hours you suddenly wake up. Although it’s before dawn the birds are already singing. You’re trying to guess the time.
Here is what you think:
It must be nearly 6 o’clock.
It may be around 5.30.
It might be 5 or 6.
Juan has dark hair and he speaks with an accent. You’re trying to guess which country he’s from.
He may be from South-America.
He must be Spanish.
He might be from Colombia.
In the following exercise, you’re going to write sentences with may be, might be, and must be.
Rewrite the sentences using the modal in brackets.
I think he’s twenty years old. (may) – He may be twenty years old.
Now it’s your turn:
1 I think she’s a police officer. (might) –
2 She seems to be an expert on microbes. (must) –
3 With a voice like that he could well be a singer. (might) –
4 The days are getting longer; it’s probably spring. (must) –
5 The demand for doctors is growing; it’s probably easy to get a job now. (may) –
6 Fiona looks about 32. (might) –
7 Damian could be in his early twenties. (may) –
8 Taking care of ten children is probably hard work. (must) –
9 Such a long poem could be hard to memorize. (might) –
For the answers, scroll down.
1 She might be a police officer.
2 She must be an expert on microbes.
3 He might well be a singer.
4 The days are getting longer; it must be spring.
5 The demand for doctors is growing; it may be easy to get a job now.
6 Fiona might be about 32.
7 Damian may be in his early twenties.
8 Taking care of ten children must be hard work.
9 Such a long poem might be hard to memorize.