站名略号的编制尽可能按该站名的第一个字的拼音的第一个（）进行排列。
参考答案：字母
用适当的介词填空。
1. I want to eat a bowl ________ dumplings.
2. He goes ________ No. 5 Middle School.
3. I like some sugar ________ porridge ________ lunch.
4. How much ________ one hot dog?
5. It's time ________ school.
6. We live ________ Canada.
7. I have supper ________ the evening.
8. What's the matter ________ you, Tom?
9. Look ________ this picture.
10. He does his homework ________ a Wednesday morning.
设f(t)连续，区域D=(x，y)||x|≤1，|y|≤1，求证：
