Experiments in the photography of moving objects______in both the United States

游客2023-10-20 49

问题 Experiments in the photography of moving objects______in both the United States and Europe well before 1900.

选项 A、were conducting
B、have been conducting
C、had been conducted
D、had conducted

答案 C

解析由后面的时间可知应填过去时态，而“before+时间”通常与完成时连用。

转载请注明原文地址:https://tihaiku.com/zcyy/3114567.html

相关试题推荐

随机试题

最新回复(0)

(1)Virtuallyeverythingastronomersknownaboutobjectsoutsidethesolarsy