Deng Xiaoping put forward the policy of “reform and open?door in 1978, China has
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Deng Xiaoping put forward the policy of “reform and open?door” in 1978, ________ China has witnessed great changes.
A．when B．since when
C．since then D．during which
试题答案
B
考查定语从句与并列句的辨析。根据后一分句采用了现在完成时态判断出应该排除A、D两项；逗号后无并列连词，应该用一个非限制性定语从句来补充说明先行词，then不能充当关系副词，也应该被排除，故选B项。