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

 A. subsidiary                                                          B. coordinate

 C. substantial                                                         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

16. All of my efforts to ______ peace failed at last.

 A. reserve                                                               B. conserve

 C. persist                                                                D. preserve

17. The laws to be made have to ______ to various special interest groups.

 A. lead                                                                    B. cater

 C. satisfy                                                                D. serve

18. Four weeks ______ for making the necessary preparations.

 A. has allowed                                                       B. allowed

 C. were allowed