英语流利说 Level6 Unit2 Part1 Learning-Talking about Modals 2
1.here is the second set of modals.
2.These modals express degrees(程度） of logical force or social expectation.
(这些情态动词表达了逻辑力和社会期许的程度）
3.must/had better/should /ought to
4.Note that none of them has a pst tense of weakened form.（弱化形式）
5.The first one, "must" indicates logical or social necessity.(n.必需品; 必要（性）; ) （跟读）
6.It expresses the strongest logical or social force.
7.The modals"should" and "ought to" assert(美[əˈsɜ:rt],vt.声称，断言; 维护)that something is probable or expected, but not necessary.
8.The modal "had better" expresses advisability.
9. In other words, if someone "had better" do something, they should do it or there may be negative consequences.
10.Therefore,"had better" has the feeling of a threat, as in (例如）"You had better be there."
11.This isn't the same as "You should do it ",which means you are expected to do it ,but without an implied threat if you don't.
1.One interesting rule is that no more than one modal can be used with any verb. (跟读）
2.There are no exceptions to this rule.
3.Therefore,it's incorrect to say"He will must be there."
4.To avoid breaking this rule, there are other words that have the same meaning, but are not modals.
5.In the case of "must", for example, we use "have to" as in "He will have to be there."
6.Similarly, we cannot say"He may can come."
7.Instead,we say "He may be able to come."
1.One last thing to note about modals.
2.They use the same form regardless(adv.不顾后果地; 不管怎样，无论如何) of what the subject is.(adv.不顾后果地; 不管怎样，无论如何)(regardless of :不管，不顾）
3.If the grammatical(adj.语法上的) subject is I, it, we or they, we use the same form, will.
4.We would never say "He wills be there."
5.But with non-modal forms, such as "have to" we must change the form to match the subject.
6. He has to be there, and I have to be there.
The modal may shows that the speaker thinks that something is possible.（跟读）
