It's believed that parks are to the city __lungs are to the body. A what B like C that D which为什么选A

A what （句中第一个are的位置是不是不对？）
你的句子是不是应该这样：It's believed that parks to the city are __ lungs are to the body.
what = sth that
人们认为，这个公园对于这个城市来说，就如同（我们的）肺相对于我们的躯体一样。

固定句式“A_is_to_B_what_C_is_to_D”句型，用来进行类比，比如“air is to us what water is to fish."

A is to B What C is to D
A 对B 来说就如C 对D 一样
不懂继续问( 天天在线 ）

固定搭配。
A is to B what C is to D. A对B正如C对D。
如：
A net is to the fisherman what is a weapon to a soldier. 渔网对渔夫正如武器对士兵。