A lot of language learning， has been discovered，is happening in the first year of life，so

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.(2012·安徽，29)
A. as
B. it
C. which
D. this

(答案→)A. asB. itC. whichD. this解析：句意：正如人们所发现的那样，许多语言学习是在生命的第一年进行的，所以在那个时期父母应该多跟孩子说话。考查非限制性定语从句中关系代词的选用。根据句子结构可知，空格处为非限制性定语从句的引导词，先行词为一个句子(即A lot of language learning is happening...)，先行词在定语从句中作主语。当定语从句为被动语态时，常用as作主语来引导定语从句；如果从句中行为动词是主动语态，一般用which作主语。故答案为A项，as意为：正如。

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