帮我看一个英语句子！

粗略翻译哈：
“众所周知，需要使用一些有效的方法来阻止这个/这种（前文说的是现象么?总之是要stop一些东西= =+）”
后面那截用了被动啦，调回来就是should make the proper use of some efficient measure to stop this。
嗯...传说中的“make use of”短语...

As is konwn = As (需要使用一些方法来stop this) is known (to all/everybody/...)
As后面本来是要加上逗号后面的那一截的，就类似于“As sth. is known...”，可是那一截太长啦，所以放到逗号后面去...就是省略的说法啦...
汗，真不知道要怎么表达哦，总之这样表达就是对的...
（↑楼主是不是感觉我说了像没说= =||）

如果要用As it is known 的话后面还要加that：
As it is know that + 逗号后面那截句子
因为it没有实质意思，只是是指代哦，所以要用从句来解释一下....
哦哦哦，越说越不明白了...直接无视我吧，汗...

飘走= =+

As it is known, ...

or

As you know, ...

是正确的。

As is known是As it is known的缩写,都可以的
the proper use 主语should谓语be made of some efficient measures 宾语to stop this动词不定式做目的壮语

As is known是正确的，写作时还常用到：as is known to all（放在句首），就是“众所周知”的意思。