下列哪个不是克令吊的安全装置（）
A.限位装置
B.吊臂角度限位
C.旋转手柄限位
D.紧急按钮
参考答案：C
A lot of students in our school were born ____ March, 1981. [ ]
A. in
B. at
C. on
D. since
最耐盐碱的树种是（）
A.柽柳
B.杜鹃
C.山茶
D.桂花
