o(∩_∩)oOnly when the whole city was covered in the thick fog

来源：学生作业帮编辑：作业帮分类：英语作业时间：2024/05/22 01:19:22

o(∩_∩)o
Only when the whole city was covered in the thick fog _______ the importance of environmental protection.
A.people realized
B.people had realized
C.did people realize
D.had people realized
请问一下为什么这题应该选择C而不是D呢?

同学,很高兴回答你的问题
正确答案确实选C
即：Only when the whole city was covered in the thick fog did people realize the importance of environmental protection.
翻译：只有当整个城市笼罩在浓雾之下,人们才会意识到环保的重要性.
解析：only 在句首时句子要倒装,句子为主从复合句,则主句倒装,从句不倒装.本句中从句的时态是一般过去时,那么主句的时态也要用一般过去时,不能用过去完成时,因为when 的意思是当...时,一般前后的时态应该是一致的,如果主句的动作发生在从句的动作之前,则主句用过去完成时,即“过去的过去”.而本句主句的动作应该是发生在从句的动作之后的,即先浓雾笼罩城市,后来人们才意思到,显然不能用过去完成时,所以D是错误的.
再给你看一道类似的例题,
Only when _____ home_____ that he had left his bag in the taxi he had taken.[ ]
A.he returned; did he realize
B.did he return; did he realize
C.he returned; he realized
D.did he return; he realized
Only when _____ home_____ that he had left his bag in the taxi he had taken.
A.he returned; did he realize
B.did he return; did he realize
C.he returned; he realized
D.did he return; he realized
答案：A
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
不明白请继续追问,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

o(∩_∩)oOnly when the whole city was covered in the thick fog The thick smog covered the whole city.It was as if a great b 英译汉 The thick covered the whole city ,It was as if a great b 阅读理解It was a very foggy day in London.The fog was so thick t The school bus was——by a thick fog. The town was covered in a thick blanket of——.(foggy) The whole city was destroyed in the earthquake. 英语填空In the old days,London was k_______ as a city of fog.The 句型转换 The plane was late because the fog was thick.（同义句转换） Th The whole city was d___in the earthquake . 英语翻译When I was lost in London,it had one of the thickest fog they found that the ground was already covered with thick no