短半径弯头
参考答案：
弯曲半径等于管子公称直径的弯头。
The new seatbelt, which is happily accepted by drivers,______ them greater freedom of movement. [ ]
A. requires
B. forbids
C. adjusts
D. allows
鞍区内最常见肿瘤是
A．垂体腺癌
B．脑膜瘤
C．胶质瘤
D．垂体腺瘤
E．畸胎瘤
