His mother’s life had been so hard that she had finally _______.

His mother’s life had been so hard that she had finally _______.
A. became mad
B. goes mad
C. gone mad
D. gone to mad
      满分：2  分
2.  He kept the bag closed _______ his sister couldn’t see the modest gift he had bought for her.
A. that
B. as so
C. so that
D. so as
      满分：2  分
3.  The USA ______ a great advanced country without the labor of the newcomers.
A. could become
B. can become
C. couldn’t have become
D. couldn’t become
      满分：2  分
4.  She had carried home her babies who were _______ sleepy to walk.
A. too
B. to
C. so
D. such
      满分：2  分
5.  The more often a fish is nearly caught, _______ it will be to interest it next time.
A. less difficult
B. the more difficult
C. the difficult