【单选题】Precaution to be observed when pouring molten metal into the pouring basin is
A.
The pouring basin should not be kept full during the pouring
B.
The pouring basin should be kept full during the pouring
C.
The metal should be poured as fast as possible to reduce the drop in metal temperature
【简答题】输尿管盆部,在男性走行于____后方并与之交叉;在女性,则在宫颈外侧约2.5cm处从后下方绕过____后行向内下至膀胱底穿入膀胱壁内。
【单选题】______ into oceans and rivers is a serious form. of pollution.