桥梁基础采用钻孔灌注桩时,混凝土强度等级不宜( )。
A.小于或等于C25B.于或等于C20C.小于C20D.小于C25
参考答案:C
____ most efficient way to understand thousands of new words is to gain ____ good knowledge of basic word information.
A.A; a.
B.The; /
C.A; /
D.The; the
高加停用后机组带负荷不受限制。