已知ax=ay，则下列结论错误的是（） A．x=y B．b+ax=b+ay C．ax_爱下问搜题

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问题选择题

已知ax=ay，则下列结论错误的是（　　）

A．x=y

B．b+ax=b+ay

C．ax-x=ay-x

D．

ax

π

=

by

π

答案

A、根据等式的性质2，ax=ay两边同时除以a（a≠0），得x=y，当a=0时，x不一定等于y，故本选项符合题意；

B、根据等式的性质1，ax=ay两边同时加b，得b+ax=b+ay，故本选项正确，不合题意；

C、根据等式1，由ax=ay可得ax-x=ay-x，故本选项正确，不合题意；

D、先根据等式的性质2，ax=ay两边同时乘以π，得到，故本选项正确，不合题意．

故选；A．

阅读理解

Water, it’s a problem for the whole world. A bottle (瓶) of water may not seem like much to us,   1  it can help the people who live in drought-hit (遭受旱灾的) areas in China.
In the past few months, many places in southwest China have  2  a serious drought. There has been very little 3  since last autumn. More than 20 million people are   4  trouble finding safe drinking water.
After learning about the drought, many people around the country helped by   5   away water, money and other resources (资源) to the people there.
Last week, the Young Pioneers and the Communist Youth League in China called on (号召) each student to give one bottle of water to the drought-hit area. In Xi’an, 900 students bought over 100 bottles of water 6 their pocket money. They also wrote their   7  on the bottles. “I hope you get more rain there. I hope you are happy.”
A bottle of water isn’t much, but thousands of bottles will be very   8 . The serious drought has also made students   9 the importance of saving water. One student said, “I have decided to take a shower twice a week   10  every day to save water.”

B．experienced

单项选择题

下列哪个β受体阻断剂有内在拟交感活性

A．普萘洛尔

B．噻吗洛尔

C．吲哚洛尔

D．阿替洛尔

E．美托洛尔