吊运井壁吊具主要由()组成
A.吊架
B.悬吊梁
C.平衡油缸
D.吊带和卸扣
参考答案:A, B, C, D
She hasn't got enough money ______ she buys the rings. [ ]
A. for which
B. with which
C. that
D. which
数据库管理系统常见的数据模型有层次模型、网状模型和 【5】 3种。