在设计对照实验时，我们应注意的问题是
A：所有变量都相同
B：所有变量都不同
C：除实验变量外，其他变量都相同
D：除实验变量外其他变量均不同
从方框中选词并用其适当形式填空
wear sing hear watch help
（1）Tony likes music and he likes ____.
（2）Be quiet! Can you ____ someone is singing a song?
（3）Tom’s aunt always ____ T- shirts.
（4）The family like ____ TV at home together.
（5）Li Lei always ____ others.
