题目内容：

单句改错

1.At that very moment my mind went completely blankly and I forgot what I was supposed to be doing.

2.The discovery was made on accident, which we hadn’t expected.

3.Every possible means have been used to prevent the pollution, but the sky is still gray.

4.This really is a useful reference book, which is worth reading the second time.

5.I think of the happy hours we spent together every time when I see these photos.

6.My uncle tells me that the key to his success is honest.

7.When I look at this picture of myself, I realize of how fast time flies.

8.Now the prices are lower, but the goods have been disappeared.

9.However, there were 20% students not adapt to the teaching method.

10.Though the problem was difficult to understand, what he said threw light in it.