阅读理解。

     Today is Sunday .In the morning, Tom gets up at 6:30. He makes his bed and wash his face at 7:30.

Then he eats breakfast. In the afternoon, he plays football with his friends. In the evening, he doesn't

watch TV. And he goes to bed early.

判断正误，正确写T，错误写F。

( )1. It is Saturday today.    

( )2. Tom gets up at 6:30.    

( )3. In the afternoon, Tom plays table tennis with his friends.

( )4. Tom doesn't watch TV in the evening.

在现代城市建设中，各种重机械发挥了很大的作用，不仅解放了生产力，更重要的是提高了劳动效率．在某建筑工地上，一台起重机将重为7 000 N水泥板在40 s内匀速提高4 m，如果所做的总功为5.6×10⁴ J，求：

（1）起重机做的有用功；

（2）起重机的机械效率；

（3）起重机的总功率．