男性，32岁，头晕、头痛多年，额窦X线检查如图所示，则最可能的诊断是（）。 A．右侧

Woman: Your dormitory room isn't very large, is it Man: I can hardly turn around in it. Question: What does the man mean

A．His room is quite small.

B．He had to walk around the dormitory.

C．It's hard to find a room in the dormitory.

D．It's his turn to look at the dormitory room.

消化道大量出血是指数小时内出血量为()

A．>1250ml

B．>750ml

C．>1000ml

D．>1500ml

E．>500ml

泵与风机发生喘振的条件有（）。

A、泵与风机具有驼峰性能曲线，并在不稳定工况区运行；

B、管路中具有足够的容积和输水管中存有空气；

C、所输送的流体流量发生变化时；

D、整个系统的喘振频率与机组旋转频率发生重叠时发生共振。

套丝M10的时候螺杆直径为（）。

A.5.8mm

B.7.8mm

C.9.75mm

D.11.75mm

请说明在使用期货合约进行套期保值时，什么是基差风险。