20. _____ China’s reform and opening up in late 1978, its quick development has aroused worldwide attention, which has made America anxious about it.
A. When B. As C. While D. Since
20. _____ China’s reform and opening up in late 1978, its quick development has aroused worldwide attention, which has made America anxious about it.
A. When B. As C. While D. Since
D
选D。 since引导一个时间状语从句，或接一个短语时主句要用现在完成时。