蛛网膜下腔出血最常见的原因是
A．先天性脑底动脉瘤
B．颅脑外伤
C．血液病
D．血管畸形
E．动脉粥样硬化
参考答案：A
一个等腰三角形有两边长分别为5cm、6cm，则它的周长为（ ）cm。
用恰当的介词填空。
1. —Where is the school?
—It's ______ Sixth Avenue.
2. The nearest (最近的) hotel is ______ the bank and the bus station (公交车站).
3. Our school is next ______ the library.
4. The bank is across ______ the police office (警察局).
5. There is a tree ______ front of my house.
