如图所示，是三峡船闸工作过程的示意图． 它是利用____原理来工作的．当阀门A打开，阀门B关闭，水从____流向下游，当它的水面与下游相平时，下游闸门A打开，船驶入闸室．

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根据短文，从A、B、C、D四个选项中选择正确答案填空。

    It's December 28th. New Year's Day is 1. Ma Li is in a 2 shop. She wants to buy a blouse 3 her mother. She is happy because she 4 a blue blouse. It looks pretty. She thinks it 5 her mother's trousers well, so she asks the shopkeeper what the 6 is. “198 yuan,” says the shopkeeper. Ma Li is surprised (吃惊的), “Too 7! What's it made of?” The shopkeeper tells her the blouse is made of silk. “Good things always 8 much,” he says.

  “But I have only 190 yuan. Can it be cheaper (更便宜)? I buy it for my mother. ”

  “9. 198 yuan is the last price. But I will lend you 8 yuan.”

  “10? We don’t know each other.”

  “Because I love my mother, too,” says the shopkeeper with a smile (微笑).

他，著名地球物理学家、国家“千人计划”专家、给地球做CT的科学家，通过探测技术，能够快速扫描海面以下很深的水域，无论是矿藏还是潜艇队都逃不过他的法眼。7年前，当他离开旅居18年的英国回到中国，有外国媒体报道：“他的回国，让某国当年的航母演习整个舰队后退100海里”。他就是黄大年！