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.
