根据句意，用括号内所给单词的适当形式填空。

1. I think _____(speak) English is more difficult than written English.

2. She is a quick _____(learn), and her English has got better day by day.

3. Be more careful! Don’t make any _____(mistake) in your writing.

4. I can't follow what you are saying. Could you please speak more _____

(slow).

5. The man laughed when he _____(realize) what had happened.