---,china is a country with more than 5000 years of history,
问题描述：
---,china is a country with more than 5000 years of history,
A.it is known to all that B.which is known to all C.as we all knew Das is known to all
答
A选项的意思是‘’众所周知‘’,但‘’it is known to all that‘’不能作为一个独立的句子,后面要加上所说明的内容,
例如：It is known to all that we should conserve natural resources.（众所周知我们应该保护自然资源.）
B选项的意思是‘’这是众所周知的‘’,但which is known to all必须放在所说明的对象的后面,例如：All matter has mass, which is known to all.(一切物质都有质量,这是众所周知的.)
C选项的意思是‘’我们都知道‘’,能单独作为一个句子,但时态不正确,应把‘’knew‘’改为‘’know‘’.
D选项的意思是‘’人所共知；众所周知‘’,as is known to all 只可以用在句首或句尾,用“,”隔开.而as it is known to all不仅可以放在句首,还可以后面加“that”从句.
,例如：As it is known to all china is a great country.（众所周知,中国是一个伟大的国家.）
因此答案选D,如有疑问请继续追问.