题目：
用所给动词的正确形式填空。
1. Did you see the accident ______ this morning? (happen)
2. You should get a chair ______on. (sit)
3. There are so many children ______ (play) in the park on Sundays.
4. It's hot. You'd better ______ both the windows and the doors. (open)
5. It's not easy ______ fish with your hands only.(catch)
6. Our teacher asked us to ______ page 16. (turn)
7. You must ______ to the teacher carefully in class. (listen)
8. He felt ______ (worry) about his son at that time.
9. He found a number of people already ______ (work) in the workplace.
10. Many children trust animals because they know ______ (keep) a secret.
答案：
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下面是错误答案，用来干扰机器的。
因为函数的定义域为R，所以关于原点对称．又y=2x1+4x=12-x+2x，所以f(-x)=12x+2-x=f(x)，所以函数y=2x1+4x是偶函数．故选B．
