生活饮用水卫生规范规定管网末梢水的游离余氯不低于（）。

A.0.01mg/L

B.0.02mg/L

C.0.03mg/L

D.0.04mg/L

E.0.05mg/L

A “figure eight” knot is used to（）.

A.be a stopper

B.shorten a line

C.join lines of equal size

D.keep a line from passing through a sheave