问题 选择题
过球的一条半径的中点,作垂直于该半径的平面,则所得截面的面积与球的表面积的比为(  )
A.
3
16
B.
9
16
C.
3
8
D.
9
32
答案

设球的半径为R,圆M的半径r,

由图可知,R2=

1
4
R2+r2

3
4
R2=r2,∴S=4πR2

截面圆M的面积为:πr2=

3
4
πR2

则所得截面的面积与球的表面积的比为:

3
4
πR2
R2
=
3
16

故选A.

完形填空

Peter wanted to know why he didn’t have many friends. The reason was he was always taking, never     1   .

One day Peter told Bill, “I’d like to give a party on Saturday. I’d like you to come and bring Martha,     2  ” “Thanks, Peter. We’d be   3   to come.” Bill answered. Peter then asked Bill to bring his violin. He said Bill and Martha sang well together. He said he was sure everyone    4  want Bill and Martha to sing for them. That was how Peter began to plan his party. Next he asked another friend, Betty, to bring a cake. “You make the  5   cake in the world. I like to eat your cake better than have one from the bakery.” Peter invited a few other friends to come to his party. He didn’t forget     6  something from each one of them. He even asked Jim and Mary Jackson to let him give the party at their house!  agreed.

The party was a big    8  . However, as the guests were leaving, they said “Thank you” to Bill and Martha   9    the music, Betty for the cake, the Jacksons for the use of the house and to others for their hard work. To Peter they just said, “Thanks for the   10  .”

小题1:A. give                B. giving               C. making

小题2:A. too                B. either              C. yet

小题3:A. unhappy             B. sorry               C. glad

小题4:A. would               B. will                C. is

小题5:A. good               B. best                C. better

小题6:A. asking              B. asked                C. to ask

小题7:A. They               B. He                  C. Them

小题8:A. successful          B. success             C. succeed

小题9:A. as                  B. in                  C. for

小题10:A. invitation        B. invite              C. ask

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