As isknown that China is a developing city

应该是As is known,China is a developing country.否则的话句子主语是什么，that China is a developing city是从句，那么
As is known 可以做主句吗？显然不可以，或者改成It is isknown that China is a developing country.

额 CHINA 是COUNTRY啦。
众所周知 中国是个发展中国家。

你是要翻译 还是要接句子啊？

正如人们所知，中国是一个发展中国家
请将 CITY 改成 COUNTRY

AS的意思就是：像。。。一样，如同，像，
在这里：AS IS KNOWN，就是：正如人们所知的那样，简说成：众所周知。
你把这个记下来吧，是一种常规用法。

正如众人所知中国是一个发展中国家.
若用as,应把that改成逗号,"as is known,"作为定语从句
或者改成It is known that China is a developing country. 成为主语从句,it为形式主语.China is a developing country是真正主语.

as is known,
it is known that两个常考，注意区分