测定渗流水体透明度时,从()透过水体观看放置在管底以下的特制纸片。
A.侧面
B.周围
C.接近底部
D.透明管上端
参考答案:D
Mother was worried because little Alice was ill ,especially_____father was away in Franc
A.as
B.that
C.during
D.if
电力线路发生接地故障时,在接地点周围将产生()。
A.接地电压
B.跨步电压
C.短路电压
D.无电压