11. We wouldn’t lose courage even if we ______ again.

 A. were to fail                                               B. would fail

 C. fail                                                          D. have failed

12. It is most important that one of the brakes on your bicycle ______ properly.

 A. will work                                                 B. has worked

 C. works                                                      D. work

13. These factories are ______ to the foreign trade company.

 A. subsidiary                                                B. coordinate

 C. substantial                    来源:91exam .org;                            D. substantive

14. Let’s sing together, ______ ?

 A. will you                                                   B. shall we

 C. won’t you                                                D. shan’t we

15. If you don’t pay your bill, they will ______ your gas.

 A. send                                                        B. frustrate

 C. discourage                                               D. disconnect