对直方图形状的观察分析，主要是看（）。A．形状是否接近正态分布 B．分布区问的宽窄

Here are two letters to George and his replies.

小题1:Alice is worrying about ________.

A. her friends   B. her marks             C. her height                   D her weight

小题2:Bob should ________ according to George’s letter.

A．take more exercise

B．talk to his friends

C．join a basketball team

D．learn some French.小题3:George advises Alice to talk to ________ for help.

A．her mother

B．her teacher

C．Bob’s teacher

D．Bob’s friends

妊娠满28周而不满37周分娩为()

A．分娩 

B．死胎 

C．胎儿宫内发百迟缓 

D．过期产 

E．早产

呼救器静止状态（）秒预报警。

A.15.0

B.10.0

C.20.0

D.30.0

简述YJ19卷烟机导纸器的保养。

通过炉墙的的热传递过程属于（）。