We use modal verbs to say how sure we are about something.
We use?must?when we feel sure that something is true because there’s very strong evidence.
当有强有力的证据的时候，我们用must去表示我们觉得某件事是真的。He must live near here because he comes to work on foot.? We don’t know where he lives but we’re sure it’s not far away.Come inside and get warm – you must be freezing out there. You’re a zookeeper? That must be very interesting.
Notice that?must?is followed by an infinitive without ‘to’.
2 might, may, could
We use?might,?may?or?could?to say that we think something is possible but we’re not sure.
当我们觉得某事可能是真的，但是我们还不确定的时候，我们用might、may和could。Did you hear that? I think there might be a burglar downstairs.?She’s not sure there’s a burglar but she thinks it’s possible. We’ll try to get there early but we may arrive late if there’s a lot of traffic. Don’t put it up there. It could fall off and hit someone.
Might,?may?and?could?are also followed by an infinitive without ‘to’.
We use?can’t?when we feel sure something is not true.
当我们确信某事不是真的的时候，我们用can’t。It can’t be a burglar. All the doors and windows are locked.?He doesn’t know it’s not a burglar but he feels sure it’s not. It can’t be far away now. We’ve been driving for hours. Where’s the map? Really? He has to work on Christmas Day? He can’t feel very happy about that.
Like the other verbs,?can’t?is followed by an infinitive without ‘to’.
Remember that all of these modal verbs–?must,?might,?may,?could?and?can’t?have other uses. These are covered in another section.