单词拼写。根据句意完成句子，在空格里写出恰当形式的英语单词，每空一词。

1. If you do the same thing over and over again, you begin to do it _________ (automatic).

2. The Impressionist paintings were __________ (有争议的) at the time they were created.

3. The teacher gave __________ (具体的) examples to show the meaning of these abstract words.

4. A teacher should not show __________ (prefer) for any one of his pupils and should treat them fairly.

5. _________ (civil) there will be destroyed if war breaks out.

长江通航里程达8万多千米，有“______”之称；我国汛期最长的河流是______．