“计划生育，丈夫有责”，现在男性结扎也是常用的节育措施之一。那么男性两侧的输精管

用适当的短语完成句子。

hear of, drop out of school, look after, look out, go abroad, be different from

1. His family is very poor,so his parents want him to______.

2. In order to improve his foreign language, Li Lei______last month.

3. ______!The car is coming.

4. Her character is mine.She is______introvert (内向), but I am the opposite.

5. Do you______Coco, she is a very famous singer.

6. Please______your grandparents,they are too old.

密度=样地内某物种个体数量/样地面积。 ( )

质量为50千克的同学站在水平地面上，他受到的重力为______牛，重力的方向是______，重力的施力物体是______；他对地面的压力是______牛，压力的方向与水平地面______，受到压力的物体是______（填“同学”或“地面”）．（g=10N/kg）

我国的消防法规体系由消防法律、行政法规、地方性法规、国务院规章、地方政府规章及（）组成。

A.消防技术标准

B.国家标准

C.地方标准

D.行业标准

已知关系模式R中，U=A,B,C,D,E，函数依赖集为FD=A→B,C→D,C→E，则该关系模式最高达到______。

A．1NF
B．2NF
C．3NF
D．BCNF