Tham khảo tài liệu 'phrasal verb 2', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | GRAMMAR SECTION 3 Necessity duty and advice 1 NECESSITY We use must and mustn t when we decide for ourselves what s necessary You mustn t keep asking for my help all the time. I don t want you to I really must be going it s getting late. I think I must We can also use must and mustn t for impersonal necessity The lead must be connected properly or it won t work. The strength of necessity varies with the situation All questions must be answered. order You must see the film - it s really good. advice We must get together sometime and talk this over. suggestion have to Although not a modal verb we often use have to and have got to more informal before verbs to talk about necessity. Have to usually suggests that someone else decides what s necessary The notice says we have to report to the manager s office. I ve got to go or my boss will wonder where I am. Because have to isn t a modal it has a past form -ing form infinitive form etc. This means we can use it in more situations than must We had to break in because we d forgotten our key. They ll have to hurry if they re not going to be late. I don t like having to wear a suit and tie. He pretended to have to leave early. 2 DUTY AND ADVICE We use should and ought to to express our opinion about what s right and wrong Drivers ought to be more considerate to other road users. it s their duty You should take this responsibility very seriously. it s your duty You really shouldn t be lifting heavy furniture at your age. strong advice criticism To talk about the past we use should have and ought to have. They suggest what happened in the past was wrong or unfortunate The Government ought to have listened. they didn t You shouldn t have worked so hard. you did We use shall as well as should and ought to to ask for advice What shall I do Do you think I should tell her 3 NOT NECESSARY To say there is no obligation to do something we use needn t don t need to or don t have to. In many instances there is little or no change in .
