管子的通球实验选用钢球直径为管内径的（）。A、70％~75% B、75%~80% C_爱下问搜题

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问题单项选择题

管子的通球实验选用钢球直径为管内径的（）。

A、70％~75%

B、75%~80%

C、80%~85%

D、85%~90%

答案

参考答案：C

单项选择题

按省、市、县、乡构成的行政系统称为：

A．完整制

B．中央集权制

C．层级制

D．职能制

完形填空

A couple of weeks ago，my friend offered to sell some of our things for us. I thought it was a good opportunity to        my 7 year old son’s room and         some toys that were no longer suitable for him to play with. We       that all the money we got from selling the toys would be his money.
The night before the       ，we loaded up the truck with toys and a little bike that was too       for him. In the yard he       the bike for the last time and then happily put it onto the truck. This little bike had at least two previous owners as far as we       .It wasn’t in the best       and was certainly not new，but the tires were       good.
We put a price of $10 on it，but it didn’t sell. So，after the sale was       ，my friend put it on the sidewalk with a sign that       “FREE，BIKE”. Within five minutes her doorbell rang. A little boy was       there. In poor English he asked whether the bike was        free. She said yes and that he could have it for       He smiled，got on the bike and rode away.
Later that evening when I told my son how much money he had made at the sale，he was very      ，shouting happily. He asked about a few of his things，wondering    they had been sold. When he asked about the bike，I told him about the little boy and that made him       .He was much happier than when I told him how much he had       .He was so happy to       that someone else would make good       of that little bike!

D．disappointed