A. 车挡
B. 挡车器
C. 停车器
D. 停车顶
30.以下属于计量工作的有A. 计量单位与单位制B. 计量器具C. 量值传递与计量溯源性D. 质量检验E. 计量管理
[单选题]30. The sweater isA.bigB.greenC.¥30D.A,B and C
[单选题]30. In fact Tom _______.A. liked glassesB.went to the wrong shopC. couldn't read at allD.knew the man in the shop
[单选题]30. There are _______in the drawer.A.10 baseballsB.12 soccer balls .C. 5 baseballsD. a tennis racket
[多选题] 对轨道端部止挡有什么技术要求()。A .强度要求B .具有防止起重机脱轨的良好性能C .应与起重机或小车上的缓冲器相互对应
[单选题]30______________-30. A showy B dangerous C exciting D harmful