直流电动机利用 ____的原理制成，把 ____能转化为 ____能。直流电动机的换向器的作用是每当线圈转过 ____位置时，它就能自动改变 ____的方向，使线圈不停地转动。

关于苏必利尔湖的叙述，正确的有（　　）

    It is Saturday morning. My father is ____  the car.  I am ____  him. My mother is ____  ____   in the kitchen.  Helen is ____ the living room. She is ____  the floor. Where is Tim? What is he doing now? Tim is in his ____ .He is ____. Ben's dog is sleeping too.