夹渣一般是由于浮渣嵌入铸坯表面皮所造成的表面缺陷。
参考答案:对
I lost my way in complete darkness and,______ matters worse, it began to rain.
A.made
B.having made
C.making
D.to make
醇类抑菌剂三氯叔丁醇常用浓度为
A.0.3%~0.5%
B.0.35%~0.5%
C.0.4%~0.5%
D.0.5%~0.6%
E.0.3%~0.6%