(单选题)

A lot of language learning, ______ has been discovered, is happening in the first year of life, so parents should talk much to their children during that period.

A.as

B.it

C.which

D.this

参考答案：A

参考解析：

考查关系代词as的用法。句意：正如人们发现的，大量的语言学习是发生在人出生后的第一年，所以家长们应该在这段时期要多和孩子讲话。从结构判断此处是非限制性定语从句，排除B、D选项；as引导定语从句译成“正如，就像”，引导的定语从句，先行词可以为主语，而且从句可以放在句中，句首。而which只能放于句尾，故选A。

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