12. Only in recent years _____ begun to realize that industry often caused pollution.
(A) have people
(B) people have
(C) people who have
(D) do people

整理一下會用到倒裝的句子：

一、否定副詞放句首：
1. only 所強調的方式狀態語、條件狀態語、地點狀態語和時間狀態語位於句首時，會部分倒裝。
Only by taking the bus can you arrive the museum.
但如果only修飾的不是狀態而是主語，則不能倒裝。
Only her mother was invited.

二、neither、nor、so之後：
1. nor
The mayor of Florida refused to resign, nor do we expect him to.

三、條件句(should 、had)
1. Should  
Should you need any help, don't hesitate to call. (如果你需要幫助，可以儘管打來。)

在這其實有if(如果)的意思，而語氣比if 更正式。

四、方向副詞在句首：
1. here、there、out、in、up、off、down、away、back......且謂語動詞為go、come、run、rush等表示位移的動詞。

Here comes the bus.
There goes the bell.
Down came the rain.
Out rushed a tiger from the wood.

資料提供自：https://tw.blog.voicetube.com/archives/18263