28 你肯定很厌倦工作 情态动词Must 和 can't

Today is Saturday. You must be very happy.  Saturdays are wonderful days for doing nothing.今天是周六，你肯定很开心。因为周六是非常美妙的，可以什么都不用做的。

A

我们用Must来表达推断某事是真的，也就是“肯定…”

Jim: My house is very near the motorway.

Bob: It's must be very noisy.

We use must to say that we feel sure something is true:

- You've been traveling all day. You must be tired.（ Travelling is tiring and you've been traveling all day, so you must be tired.）

-''Jim is a hard worker' 'Jim? A hard worker? You must be joking. He's very lazy.'

- Carol must get very bored in her job. She does the same thing every day.

 We use can't to say that we feel sure something is not possible:

- You've just had lunch. You can't be hungry already.（ People are not normally hungry just after eating a meal. You've just eaten, so you can't be hungry.）

- Brian said he would definitely be here before 9.30. It's 10 o'clock now and he's never late. He can't be coming.

- They haven't lived here for very long. They can't know many people.

 Study the structure:

B

For the past we use must have （done ）and can't have （done）. Study this example:

-George is outside his friend’s house. He has rung the doorbell three times but nobody has answered. They must have gone out. （Otherwise they would have answered.）

- The phone rang but I didn't hear it. I must have been asleep.

- I've lost one of my gloves. I must have dropped it somewhere.

- Jane walked past me without speaking. She can't have seen me.

- Tom walked straight into a war. He can't have been looking where he was going.

Study the structure:

Couldn't have... is possible instead of can't have...

- She couldn't have seen me.

- Tom couldn't have been looking where he was going.