() 20. Studying in group is necessary you want to do well in school.

   A. if   B. until   C. unless   D. though

() 19. The man will have to wait all day the doctor works faster.

   A. if   B. unless   C. whether   D. that

() 18. My brother and I look different we are twins.

   A. unless   B. as

   C. though   D. because

() 17. 一Please remember to say goodbye to Mr. Smith when you tomorrow.

—Sure,I will.

   A. leave   B. will leave

   C. left   D. have left

() 16. —Mum, shall we have lunch?

—We will have it when your dad .

   A. when;returns   B. where;returns

   C. where;will return   D. when;will return

() 15. Although he is considered a great writer,.

   A. his works are not widely read

   B. but his works are not widely read

   C. however,his works are not widely read

   D. and his works are not widely read

() 14. I'll go with you as soon as I my work.

   A. will finish   B. shall finish

   C. finish   D. finished

() 13. —I hear the famous singer Liu Huan may come to Xiangyang next month.

—Really? he comes,my younger sister will be very excited.

   A. If   B. Until   C. Unless   D. Before

() 12. I don't know if she to my birthday party tomorrow. If she,I'll be very happy.

   A. comes;comes   B. will come;comes

   C. comes;will come   D. will come;will come

() 11. Making friends is not easy. Sometimes it can take years you become true friends with someone.

   A. before   B. after

   C. because   D. unless