阅读下面短文，选择方框里A—E五个句子，分别填入文中空缺处，使补全后的短文意思通顺，结构完整。（5分）
One day, a teacher was giving a speech to his student. He held up a glass of water and asked the class, “小题1:
”
The students’ answers ranged from 20g to 500g.
“小题2: It depends on how long you hold it. If I hold it for a minute. It is OK. If I hold it for an hour, 小题3: If I hold it for a day, you will have to call an ambulance（救护车）. It is exactly the same weight, but the longer I hold it, the heavier it becomes.”
“If we carry our burdens（负担）all the time, sooner or later, we will not be able to carry on, the burden becoming increasingly heavier.”
“What you have to do is to put the glass down, 小题4:”
We have to put down the burden sometimes, so that we can be able to carry on.
So before you return home tonight, put the burden of work down.小题5:You can pick it up tomorrow.
Whatever burdens you’re having on your shoulders, let it down for a moment if you can.
A．I will have an ache in my right arm.
B．How heavy do you think this glass of water is?
C．rest for a while before holding it up again.
D．It does not matter on the weight itself.
E．Don’t carry it back home.
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求曲线C距离xoy面最远的点和最近的点．