Chinabegantoopentotheoutsideworldinthelate1970s．

問題詳情：

China began to open to the outside world in the late 1970s．_________, there have been great changes in the country．

A．By then            B．As a result        C．At last             D．In all

【回答】

B

知識點：介詞和介詞短語

題型：選擇題