It was not until man had learned how to make iron and steel that the construction of various...

It was not until man had learned how to make iron and steel that the construction of various...
It was not until man had learned how to make iron and steel that the construction of various machines________possible.
A.were made
B.made
C.had made
D.was made
英语人气:924 ℃时间:2020-02-26 05:45:36
优质解答
D.直到人类学会炼制金属,各种机械的制造才成为可能.制造是单数,而且是被人做.时态发生在制金属之后.
我来回答
类似推荐
请使用1024x768 IE6.0或更高版本浏览器浏览本站点,以保证最佳阅读效果。本页提供作业小助手,一起搜作业以及作业好帮手最新版!
版权所有 CopyRight © 2012-2024 作业小助手 All Rights Reserved. 手机版