阅读下面的短文，在空白处填入一个适当的词，或填入括号中所给单词的正确形式。

    Once upon a time, there was man called Yu Gong. Yu Gong and his family began (move) some of the earth and stones to the sea. One day, a man saw Yu Gong and (he) children working on the mountains. He told Yu Gong he could never (do) it because he was old and weak. As soon as the man finished (talk), Yu Gong said that his family could continue moving the mountains. His family would live and grow the mountains could not get bigger. Yu Gong and his family kept on (work) day after day and year year. (final), a god was moved by Yu Gong, so he (send) two gods to move the mountains. This story tells us that you can never know what's possible unless you try to make it happen.