9. Birds flew back because the fine environment . _________

8. I’m fed up waiting for her letter . ________

7. I don’t like going out lonely after dark ._________

6. The nearest village is about one hundred miles far away ._________

5. You are terrible ill . You’d better stay in bed . ________

4. Even he is old , my grandpa works on the farm . ________

3. They have never had the chance to be there ago .______

2. The tomatoes I picked are much more redder than yours . ______

1. It took Jack two hours climb the mountain . _______

2. It's too hot． Let's go s________ in the river.

　析：以上两题考查学生对动词形式变化的掌握情况。做此类题时，应根据句意确定用哪个动词，然后再根据其他线索来判断用动词的哪一种形式(原形、第三人称单数、现在分词、过去式、过去分词)。在第1题中，因前面有助动词did，故用动词原形understand；第2题中go swimming为短语，所以填swimming。

　例：We're finishing the second unit． Now let's go on with the t________ one．

　析：上题考查了数词。对于数词应根据句意判断出是用基数词还是序数词形式，根据前面的the可知应用序数词third。同时，应注意某些数词的特殊形式，如：first， third， fifth， ninth， twelfth， twentieth。