从下列各句四个选项中选出一个最佳答案，并写在答题纸相应的位置上。

1.Commercial television has mixed entertainment and advertising.If you want

 the entertainment,you have to _______ the advertising.

  A. come up with                                     B. put up with

  C. keep up with                                      D. catch up with

2.Many of the ideas which scientists tell us have no foundation _______ with mixtures of food.

  A. have to doing                                     B.having to doing

  C. have to do                                          D. having to do

3.Perhaps this would be a good chance _______ promotion.

  A. being got                                                  B. got

  C. getting                                               D. to get

4.How can you keep the machine _______ when you are away?

  A. running                                              B. ran

  C.to run                                                 D. being run