a waste of time

基本解释

Attempting to change someone is a waste of time and energy.
嘗試改變別人是一件浪費時間和精力的事情。
At the same time, other students in the same class already have the skill down cold, so further practice for them is a waste of time.
同時，同一個班級的其他學生可能已經熟練掌握了這項技能，所以繼續練習對他們來說衹是浪費時間。
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An architectural description, like any deliverable, needs to be created for a purpose and an audience, otherwise creating it is a waste of time.
一個架搆描述，如同任何可交付的産品，是需要爲了某個目標和受衆而創建的，否則衹是浪費時間。

In addition,news agencies provide updates and companies share product information through Twitter Some critics say Twitter is a waste of time that takes people's attention away from their work.
I think it's terribly important to keep the distinction in the back of our minds even if we find it, in practical terms, well nigh impossible and possibly even in many contexts a waste of time to be perpetually enforcing it.
你們一定要牢記這個區別,這實在是太重要了，盡琯有時我們發現在一些的文本中這種區別很微小,看上去不值得花時間去研究或使用。
耶魯公開課 - 文學理論導論課程節選
The last one that we saw was a complete waste of time.
我們看的上一部這種電影完全是浪費時間。
There is no 實戰 - SpeakingMax英語口語達人

To call a business plan a waste of time seems a bit heavy handed.
FORBES: Why Business Plans Don't Work And 'Pivoting' Is Nonsense