阅读下面短文，在空白处按要求填入适当的单词或括号内单词的正确形式。

    Martin is a manager. His computer and phone (be) important for him. In the office, he  (work) on the computer. When he isn't in, he can work on (he) phone. How can he do that? The phone can work like  (冠词) computer. That's really good  (介词) his work.