用单词的正确形式填空。

1. l'm eager _   __  (join)the art club.

2. He promised_     __(wait) for me at the gate of our school.

3. Having read Unit 5,I went on___   _(read) Unit 6.

4. After a short break he went on       _  (write) the letter.

5. She spent about half an hour    __    (send) the messages to her friends.

提高抽提贫溶剂量时不用考虑回流芳烃量的大小