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问题 填空题
连续掷两次骰子得到的点数分别为m，n，则直线y=
m
n
x与圆x2+（y-3）2=1相交的概率是______．
答案

由题意，直线与圆相交，由圆心到直线的距离小于半径1，圆心（0，3），直线方程为mx-ny=0故有

|3n|
m2+n2
＜1，即8n2＜m2

当n=1时，m可取3，4，5，6；当n=2时，m可取6，故使得直线y=

m
n
x与圆x2+（y-3）2=1相交的种数共5种

连续掷两次骰子得到的点数分别为m，n，所组成的数对的总数为36

故续掷两次骰子得到的点数分别为m，n，则直线y=

m
n
x与圆x2+（y-3）2=1相交的概率是
5
36

故答案为

5
36

单项选择题

尖锐湿疣的潜伏期为( )。

A．3～7天
B．10～14天
C．15～28天
D．1～3个月
E．5～6个月
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填空题

The other day my brother Tom was beginning his 56.______
motorbike then our neighbor, Mary came out and asked 57.______
him if he was going near the station. So he offered her a lift.
She got at the back of the motorbike and 58.______
they drove away. Just before they reached to the station 59.______
a policeman waved to them to stop. "Excuse me, sir," he said,
"You are not sitting on that motorbike properly. "
"What’s matter with the way I’m sitting" my brother 60.______
asked in surprise. "Not you sir. It’s a young lady," said 61.______
the policeman, "In this country side-saddle(偏座) is not62.______
permitted when one ride a motorbike．”Mary made an excuse 63．______
that she was from Italy，where it isn’t．considering to 64．______
break the law when people take the side-saddle．
The policeman shook head and drove away． 65.______
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