—I cant work out this problem. —. Lets ask the teacher.

单项选择题In China as well as many other countries around the world，greathave been made to reduce the amount of carbon emission.

单项选择题With an examination，the students felt relaxed and enjoyed themselves the whole night.

单项选择题—he managed to get the information—Oh, a friend of his helped him.

单项选择题—Which of the two ties would you like to wear—.You know Im not particular about ties.

单项选择题—John，why did you make no reply to me when I called you in the street—Sorry,Jim.Ito my friend on the phone.