数轴上A对应的数为a，B对应的数为b，且满足|a-12|+|b+6|=0，O为原点，
（1）求a，b的值，并在数轴上标出A、B．
（2）数轴上A以每秒3个单位，B以每秒1个单位的速度同时出发向左运动，在C点处A追上了B，求C点对应的数是多少？
（3）若点A原地不动，点B仍然以每秒1个单位的速度向左运动，M为线段OB的中点，N为线段AB的中点，在点B的运动过程中，线段MN的长是否变化？若变化说明理由；若不变，求出其长度．
（1）∵|a-12|+|b+6|=0，
∴a-12=0，b+6=0，
解得a=12，b=-6，
在数轴上表示为：
（2）设时间为t秒，则
3t-t=12+6，
解得t=9，
C点表示的数为-6-9=-15；
（3）B点表示的数为-6-t，
∴M点表示的数为-3-
，t 2
N点表示的数为3-
，t 2
∴|MN|=|（3-
）-（-3-t 2
）|=6．t 2
Mr Green had a little boy. Every day had work he came home and played with his son. One night ,while Mr Green was at work, he __41__ that he had extra work to do for the evening ,and that he wouldn’t be able to play with his son._____42____ he wanted to give the boy something to keep him __43__. So , looking around his office , he saw a 44 with a large map of the world on the cover(封面). He got an ___45 ____ He removed the map , tore(撕) it up into small pieces and put all the pieces in his coat pocket. When he got home , the little boy came running to him and was ready to play. Mr Green ___46___that he had extra work to do and couldn’t play at the moment . Then he ___47__ all the pieces of the map and put them on the table . He said to the boy,”_48__” was a map of the world, and ___49___th time you put it back together, my extra work will be finished, and we can ___50___”. Surely, this would keep the child busy for ___51___ , he thought. About half an hour later the boy came to Mr Green and said,” Okay, it’s ___52___ . Can we play now?” Mr Green said ,“That’s amazing!_____54 did you do that?” The boy said, “It was 55 . On the back of the page was a picture of a man . When I put the man together the whole world fell into place.”
小题9:A .by B at C. in D. for 小题10:A .work B play C. eat D. sleep 小题11:A .weeks B days C. minutes D. hours
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