以ANSI冠名的标准属于（）。A.国家标准  B.国际标准  C.行业标准  D.项

已知直角三角形的两直角边为3和4，则第三边为         .

切线位摄影位置属于（）

A.正住

B.侧位

C.斜位

D.轴位

E.特殊位

滑升模板安装呈上口小下口大的锥形，结构断面厚度以模板上口以下()模板高度处的净间距为准。

A.1/2

B.1/3

C.2/3

D.2/5

阅读理解。

     The organization,Keep Time for Children,was started in 2002 to make people realize the importance

of family time on weekends,particularly for families with school age children.   1   We will try to help

parents take one day off on weekends to be with their family.

        2    What children want and need most is to spend time with their parents,not with toys or taking

part in activities.But with more and more people working on weekends,many children of school age don't

see their parents anywhere near as often as they should.

       3    The movement is designed for families of all types and sizes under increasing pressure to work

on weekends.Because weekends are the very time when school age children are at home and in need of

their parents.we are going to put forward a Family Day Bill(议案) to the government.   4    It is aimed to

solve the problems of increasing"shift (换班的)parenting"and of young children being left "home alone

"on weekends.

        5   If parents have a day off,they can spend a lot of time and energy with their children to share their

happiness.

A. Keep Time for Children is now starting a movement.

B. The law is likely to make sure that parents take good care of their children.

C. Our aim is mainly to encourage parents to spend time with their children.

D. An American set up the organization.

E. It would give every parent of children under the age of 16 the right in law to a weekend day

    off each week.

F. Our time is the most important thing that we can give our children.

G. Parents who do not share enough time with their children are to blame.

甲醇精馏单元短期计划停车时，操作第一步是（）。

A、切除加热蒸汽

B、关闭入料

C、关闭回流

D、系统退液