问题
完形填空
________ is known to us all that the world weather is getting warmer and warmer.
答案
It
that the world weather is getting warmer and warmer是真正的主语，it是形式主语。
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________ is known to us all that the world weather is getting warmer and warmer.
It
that the world weather is getting warmer and warmer是真正的主语，it是形式主语。