One of the tennis rackets broken when th

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问题选择题

One of the tennis rackets broken when they found them.[ ]

A. is

B. are

C. were

D. was

答案

答案：D

解答题

已知圆C：x²+y²-8y+12=0，直线l经过点D（-2，0），

（Ⅰ）求以线段CD为直径的圆E的方程；

（Ⅱ）若直线l与圆C相交于A，B两点，且△ABC为等腰直角三角形，求直线l的方程．

选择题

China’s first compulsory safety regulation on primary buses, which requires every seat to have a seat belt, will ____ on July 1.

A．have an effect

B．take effect

C．bring into effect

D．come to effect