【单选题】We need to __________ an eye on all the activities to make surer that people stay safe.
【单选题】It's normal to spend two or three years working in one's country before working_____.
【单选题】We need to ________an eye on all the activities to make sure that people stay safe.
【单选题】汽车变速器 ( ) 的主要作用是改变转矩、转速和旋转方向。 A. 变速操纵机构 B. 变速传动机构 C. 安全装置 D. 齿轮