可卸代型牙颈缘距离代型底面大约（） A.1mm B.5mm C.10mm D.15m

替代互换也存在风险，其风险主要来自于()。 A．基准利率变动的风险 B．全部利率反向变化 C．价格走向与预期相反 D．纠正市场定价偏差的过渡期比预期的更长

When I had something difficult to do， I used to ask my mother for help. But she always said， “Do it yourself，dear.” I was not     1    at all. I thought she was the 2    mother in the world!

For example，one day， I decided to     3   some friends to my home. My bedroom was not in order. Books were everywhere. And I didn’t make the bed. I asked my      4   to help me clean it，   5      she still said，“Do it yourself，girl.”

Because of my “lazy mother”，I have to     6    my clothes and clean my room. I have to help my parents      7    I even have to go to the dentist by myself. It is really hard for me to do everything well，but I have learned     8   .

As time goes by， I understand my mother. She makes me clever and diligent (勤奋的)    9   a great mother! A     10  mother is worth（等值于） one hundred teachers! Don’t you think so?

小题1:A. old             B. glad             C. thin

小题2:A. tallest           B. most foolish      C. laziest

小题3:A. leave            B. invite           C. visit

小题4:A. mother          B. father           C. brother

小题5:A. or              B. when           C. but

小题6:A. wash           B. lead            C. knoc

小题7:A. do housework    B. go swimming     C. go camping

小题8:A. on show         B. by mistake       C. a lot

小题9:A. Which          B. What            C. Who

小题10:A. young         B. good             C. happy

根据发动机工作原理，分析气环的作用？

在城市通信明线线条与树木之间的最小水平距离为（）米。

A.1.25

B.1.50

C.2.0

D.2.5