C. When                                                             D. Except

5. The products you require are   _______ , but we can offer you a substitute.  

A. sold out                                                          B. heavily committed

C. dropped                                                         D. out of stock

6. If you are prepared to increase your _______ to 15%, we shall be pleased to purchase the complete stock.

A. price                                                              B. sales volume

C. discount                                                         D. cost

7. We send you our congratulations on your increased business with us and look forward to further increases   _______ our mutual benefit.

A. in                                                                  B. to

C. with                                                               D. for