选用is，am，are，填空。

1. —What _______ your name?

    —I _______ Daming.

2. This _______ my son, Yangyang.

3. Hello! My name _______ Lucy.

4. —How _______ your mother ?

    — She _______ fine, thanks.

5. Jack and Tom _______ my friends.

在变、配电系统中用母线涂色来分辨相位，规定用（）三色分别代表L1、L2、L3三个相序。