用所给的单词的适当形式填空，使句子意思完整通顺，每条横线限填一个单词。

1．1 couldn't understand why he was so       （interest） in the invitation.

2．He did the work very       （ care）. Everybody said he had done a good job．

3．I met an old friend of       （I） in the Summer Palace last Sunday.

4．Many new       （potato） will grow from one potato planted in the ground．

5．We hope it will be       （sun）  tomorrow, for our picnic．