阅读短文，选出合适的词，将单词写在横线上。

sad, sweet, grapes, cannot, round

    One day，a fox sees some nice____．They are purple and____．But the grapes are high．The fox____get and eat them．A bird can eat the grapes．She likes the sweet grapes．The fox is____and angry. He says those grapes are sour. They are not____.