从方框内选出单词，用其适当形式填空。每空格限填一词，每词限用一次。

1．Friday is the ________ day of a week．

2．Xiaomeng is a popular ________ at CCTV Station．

3．－How do you know that autumn has arrived?

－One way is that the tree ________ become yellow or red．

4．Mary becomes ________ than before because she exercises every day．

5．My friends and I may not have time to chat at school．But we can do it on QQ．It's very ________ to our friendships．

6．People often say that money can't buy happiness(幸福)．But some scientists think ________．They say it can make us happy, but only if we spend it on someone else．