It's disbennifit to become protected film if change the velocity of flow frequently.

频繁改变水的流速不利于器材料表面形成保护膜，而保护膜对于防腐蚀是至关重要的。

Filter bed should be exposurd as less as possible because alternation of exposure and immersion is disbennifit to the penetrability of filter bed.

据水质资料分析了水源水质安全保障。

Our country practices tail system,and takes direct mode of inherit.It is very disbennifit to protect debtee because there is not efficiency supervision to haeres.So it is necessary to restrict haeres.

我国实行限定的度,又采取的是直接的方式,缺乏对人有效监督的情况下,对债权人的保护极为不利,有必要对人予以限。