_________,Tom couldn't get his car to start.

选A
这里是As引导让步状语从句倒装的用法
动词原形 + as / though + 主语 + 动词
Object as you may,I’ll go.纵使你反对,我也要去.
Try as he might,he couldn’t solve the problem.尽管他想方设法,却未解决这个问题.Search as they would,they would find nobody in the house.无论怎样搜查,他们在房子里仍然没有找到一个人.
Dislike him as we may,we must acknowledge his greatness.尽管我们不喜欢他,但必须承认他的伟大.
Lose money as I did,we got a lot of experience.钱虽然丢了,我们却得到了许多经验.Fail in the election as he did,he became famous for his fiery speech against slavery.尽管落选了,但他却以其反对奴隶制的激烈演说而出了名.
【说明】主语后的动词通常为 may,might,would,did 等情态动词或助动词(若表示情态意义,则选用情态动词；若陈述事实,则用 did,do 等助动词).
真心为您服务!

选A，这是一个倒装句，正常的语序是Tom tries as he may,but he couldn't get his car to start.
Tom 尽了自己的努力去尝试，但是他还是不能发动他的车子。
用倒装句更强调Tom 尝试的次数多。

供参考~

A
呃。抱歉我也不知道为什么。。读着顺。呼唤大神。

A.这是一个状语从句，as从句 放在主句之前，需用倒装语序。从句中的表语、状语或动词原形置于拒收。若表语是名词，前置时要省略冠词。如：Child as he is, he knows a lot.

选A，英语中固定格式，将动词或形容词提到句首表示强调

选A，as引导的状语从句要倒装

A 让步状语