铺设楼地面面层的水泥混泥土，其坍落度应控制在（）
A、不大于30mm
B、35~50mm
C、1.5~2mm
D、80~100mm
参考答案：A
.It is widely accepted that young babies learn to do things because certain acts lead to ______.
rewards B.prizes C.awards D.results
应用激素的副作用是( )
A．消化道溃疡B．骨髓抑制C．电解质紊乱D．血尿E．低血钙、低血糖
