单词填空，用括号内所给单词的正确形式填空。

1. Our beautiful classroom _______(clean) every day.

2. In order to improve Mary's self-confidence, her teacher asked her to look at _______(she) in a

     mirror every morning and say "I'm the best."

3. She was very _______(happy) to fail the final exam.

4. Here are _______(tomato) noodles. They smell good!

5. Trust him! He has no difficulty _______(work) out the problem.

6. Cleaners clean the street every day. Their work is _______(true) common.

7. More and more people all over the country are worried about food _______(safe).

8. Windy does _______(badly) in P.E. than me.

你知道全世界天然气的产量和储量吗？