1.  I couldn't.

2.  I could derstand .

3.  After class we could played badminton .

4.  When we reached Xie Chao Hill, we couldn't held crying.

5.  We could listening the English programme everyday in the morning.

6.  I couldn't using my time freely.

7.  If you are lazy, hte God couldn't hlep you when you are in trouble

8.  If they engage in different works , they could not concentrat on their minds.

9.  They couldn't success .

10.  How could the old man who walks with two canes run?