化工污染来源是()。
A、燃烧的气体
B、反应产品
C、反应完全
D、反应副产品
参考答案:D
No one can imagine the difficulty he had _______ his son to get rid of the habit of playing computer games.
A.persuading
B.to persuade
C.persuaded
D.persuade
什么是光隔离器?