Ateachendofthetube,onewhichgatherslightandonewhichmagnifiestheimage.A.aretwolensesthereB.aretheretwolensesC.twolensesareD.aretwolenses答案是D为什么呢这句是句倒装句，大意是什么，还有怎么看

Question

At each end of the tube ________,one which gathers light and one which magnifies the image.
A.are two lenses there B.are there two lenses
C.two lenses are D.are two lenses
答案是D为什么呢
这句是句倒装句，大意是什么，还有怎么看出这是句倒装的？

Answer 1

原句应该是：
There are two lenses at each end of the tube, one which gathers light and one which magnifies the image.
管子的两端各有一个棱镜,一个聚光,一个放大.
倒装以后,应该是：
At each end of the tube (there) are two lenses, ...
其中there可以省略,就是答案D了.