搜题请搜索小程序“爱下问搜题”
问题 选择题

使用显微镜观察时，用于固定玻片标本的结构是(   )

A．粗糙焦螺旋

B．细准焦螺旋

C．压片夹

D．遮光器

答案

答案：C

A和B，焦螺旋可以调节镜筒，使镜筒上升或下降．粗准焦螺旋使镜筒升降的幅度大，一般先用粗准焦螺旋找到物像；细准焦螺旋使镜筒升降的幅度较小，一般是用粗准焦螺旋找到物像后，用细准焦螺旋将物像调清晰．

C、压片夹在载物台上，固定玻片．

D、遮光器的作用是调节光线的强弱．上面有大小光圈，当外界光线较强时用小光圈；光线较弱时用大光圈, 可用来调节光线强弱的结构．

故选：C

阅读理解

阅读理解。

     Christmas (圣诞节) is December 25. It's the most important holiday in America.

     People like to send Christmas cards to their friends and they buy gifts for their family and friends before

Christmas.

     Christmas Day is a day for family reunion (团聚). The family come together and sit down to have a meal

in the afternoon. On Christmas Day people go to church (教堂) to listen to Christmas Carols (颂歌). Children

are very happy on that day, and they can get a lot of gifts.

1. ________  is the biggest festival in America.

A. Christmas

B. New Year

C. Thanksgiving Day

D. Teachers' Day

2. Many people can get some ________ before Christmas.

A. work

B. cards

C. new clothes

D. cards or gifts

3. The family often have ________ together in the afternoon on Christmas Day.

A. a meeting

B. a meal

C. a ball

D. match

4. Children like Christmas Day very much, and they can ________.

A. get many gifts

B. watch TV all day

C. sing Christmas songs

D. go to the concert

5. Children like Christmas Day very much, and they can ________.

A. get many gifts

B. watch TV all day

C. sing Christmas songs

D. go to the concert

查看答案
多项选择题

滴虫性 * * 炎的临床表现包括( )。

A．脓性泡沫状白带

B．外阴瘙痒

C．性交痛

D． * * 壁皱褶消失

E． * * 黏膜有散在出血斑点
查看答案