–-You should be _______ careful when you take the chemistry exam.---I agree. In this way, I will make _______ mistakes.

—Have you ____ joined in a dragon boat race?—Yes，I have．

——Do you want to watch this video?—— No, I think it’s ____. Let’s go to the movies.

—Do  you think this book is ______difficult for children to read ？

The math problem is _______ difficult and _______ of them can work it out.