He thought that ___ A.the effort doing the job was not worth B.the effort was not worth in doingthe job C.it was not worth the effort doing the job D.it was not worth the effort by doing the job 正确的答案和具体理由以及意思

答案：C
意思：他认为不值得费劲/力气做这个工作。
原因：it为从句中的形式主语，真正的主语为doing the job;D错在加了一个by,没有凭借等的意思。

选B 理由：be worth doing sth. "……某事值得被做 比如：The question is not worth discussing again and again。这个问题不值得一次又一次的讨论。

C 正确
it was not worth the effort doing the job
it 形式主语doing the job 实际主语
A 要改成the effort to do the job effort 后面跟不定式
B 去掉 in
D 去掉by

选c，这句话的意思：他认为为了这个工作付出努力是不值的。
这句话考的是worth的用法：worth做形容词有一下几种搭配
(1)something is worth something
例：The exhibition is worth a visit.
(2)it is worth (something) doing something.这种用法实际就是把第一句中something用it（形式主语）代替，真正主语是doing something，意思是：doing something值得something。
至于A答案，只能解释为现在分词doing the job作定语修饰the effort，但二者不是主谓关系，所以不能选。