2013年度国家科学技术奖励大会在北京隆重举行，中国科学院院士、中国科学院大连化

B

I am going to tell you an unbelievable story. This afternoon a __41___(poor)  dressed gentleman came into my restaurant. Nobody knew who he was and __42___he came from. After __43___(sit) down, he ordered a lot of food. He stared at it and then _44___ (eat) it up very quickly.

To be_45___, we doubted whether the man was able to pay for the food. When he was asked to pay the bill, the gentleman asked if we would mind__46__ (wait) just a few minutes. Then we were _47___ (shock) to see that he took a million pound bank note. __48__(fortunate), we could not change the bank note as it was too large. So I gave this strange but very rich man a _49__ dinner, in the hope__50__he might come to our restaurant again.

如图所示，一质量为0.5kg的小球，用0.4m长的细线拴住在竖直面内做圆周运动，求：（g=10m/s²）  

（1）当小球在最高点时速度为4m/s，细线的拉力是多少 ？

（2）当小球在最低点时速度为m/s，细线的拉力是多少

结束了“凤阳地多不打粮，磙子一住就逃荒。只见凤阳女出嫁，不见新娘进凤阳”现象的是（）

A.粉碎“ * * ”

B.恢复高考

C.实行包产到户

D.拨乱反正

小车车轮踏面中心线间的距离，称为天车的（）。

A.轨距

B.跨度

C.轴距

D.差距

金属的毒性？