fruitless
单词辨析：
指努力、希望、搜寻等未能获得想要的结果的。
He underwent a knee operation in the vain hope of getting into the team.
他做了膝盖手术，徒劳地指望能进入该队。
She raised her head in a vain attempt to hold back the tears.
她仰起头，却无法忍住眼泪。
指行动、计划等没有成功的。
an abortive takeover bid by the larger firm
由较大公司提出的夭折了的并购
There is no record of the abortive military coup.
没有关于那次未遂的军事政变的记录。
尤指付出很多努力却无成效的。
So far, their research has been fruitless.
到目前为止，他们的研究工作毫无结果。
The fruitless attempt to settle the dispute disappointed him.
试图解决争端的努力白费了，这让他很失望。
侧重指人或事物未能发挥应有之作用的。
The army has proved ineffective in protecting the local civilians.
军队没有起到保护当地平民的作用。
This special stain remover was almost ineffective in removing the soup stain.
这种特效去污剂基本去不掉汤渍。
The policy proved ineffective in dealing with the problem.
事实证明该政策未能解决问题。
相关例句：
They struggled for freedom, but their efforts were fruitless.
他们争取自由，但努力都是徒劳。
I spent a fruitless ten minutes walking up and down the high street, desperately avoiding eye contact with passers-by.
我在大街上一无所获来回走了10分钟，其间还要拼命地躲避路人的目光。
Delivering an application without its key functionality would be fruitless.
交付不包含关键功能的应用系统是没有意义的。
These tendencies are all fruitless.
这些倾向都是无益的。
His struggle with adversity be fruitless.
他徒与不幸挣扎而毫无结果。
We now see how fruitless and illusory these missions were.
我们现在明白了这些任务纯属徒劳虚幻。