Chọn đáp án đúng: The mail is supposed ... before noon

Question 16: The mail is supposed …………….. before noon.
a. to be delivered                      b. to deliver                              c. being delivered                     d. delivering
Question 17: I expect ………….. at the airport by my uncle.
a. to meet                                 b. meeting                                c. being met                              d. to be met
Question 18: I’m interested in …………. my conversation skills.
a. improved                              b. being improving                   c. improving                             d. improve
Có giải thích