外研选修6山东临朐第二中学Book 6 Module 1 Period 4课件
外研选修6山东临朐第二中学Book 6 Module 1 Period 4课件第3页

a. You must arrive on time at a party. You have to arrive on time at a party. Which of the following is true? a) They both indicate an obligation. b) They are only suggestions about what to do. c) The first one is an obligation, the second one is a suggestion.