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％
