1.My cat would not have bitten the toy fish, ___ it was made of rubber.

D.had she known

2.___ are inert outside living cells, but within the appropriate cells they can replicate,causing viral diseases in the organism.

D.Despite viruses

3.___ your body does after the stimulus has acted is called the response.

D.That

4.___, astronomy is a field in which amateurs can make significant contributions.

D.Unlike most other sciences

5.Take your handbag and hang it ___ you can find enough space.

來源:可可英語 http://www.ccdyzl.cn/tem4/201506/377589.shtml