若以连续掷两枚骰子分别得到的点数a与b作为点M的坐标，则点M落入圆x2+y2=18内(不含圆周)的概率是( )．
A．
B．
C．
D．
E．
参考答案：D
解析：
[解] 掷出的点数a，b作为点M的坐标．这样的点有62=36个，落入圆x2+y2=18内的点有：(1，1)，(1，2)，(1，3)，(1，4)；(2，1)，(2，2)，(2．3)；(3，1)，(3，2)；(4，1)．共10个．
故所求概率．
故本题应选D．
| 完形填空。 Charlie Leng spent a few months saving up (积蓄) seven dollars. He wanted to 1 a model plane and went to the shop with the money. On the way, Charlie 2 a little boy crying on a corner of the street. "_ 3 are you crying?" Charlie asked. "Three big boys _ 4 _ my four dollars just now,"the boy said. "I was 5 to buy some exercise books, but now I can't. " Charlie thought of the 6 dollars in the pocket. He thought of the model plane and the poor _ 7 Charlie wanted to walk away, 8 he did not. 9 he gave four dollars to the boy and went home. Charlie 10_ happy. Do you know the reason? He was happy because the little boy was happy. | ||||
|