U形弯可替代两个（）弯头，经常用来连接上下配置的两个圆翼形散热器。
参考答案：90度
In China, the number of cities is increasing ________ development is recognized across the world.[ ]
A．where
B．which
C．whose
D．that
简述葡萄胎患者刮宫术后采取预防性化疗的指征。
