翻译：我们知道对于9年级的同学来说获得更多的知识是很重要的

As we know that, for students in Grade 9, to learn/gain more knowledge is vital/very important.
As we know that it is very important for students in Grade 9 to learn/gain more knowledge.
另外laterthannever - 举人 四级的句子里，get是不能作句子主语的，要用getting或者to get作主语。

As we know that get more knowledge is important for us in Grade 9.

As we all know that get more knowledge is very important to the students in Grade 9

听我的，比较专业一些！
As we know that knowledge accumulation is quite important for those ninth graders.