Isn't there something better you should be doing?
你沒有別的事要去做的么？
Who are you to tell us what we should be doing?
你是什么人，可以要求我們做這做那？
They feel they should be doing something useful with their time.
他們感到應該用他們的時間做些有用的事情。
You know what we should be doing.
你知道我們該干嘛嗎。
I just feel like there are more important things I should be doing.
我覺得有更重要的事該做。