Be on another planet; what planet is sb on?

Used to describe that sb's ideas are not realistic or practical (表示某人的想法完全不切實際)你在想什么啊,異想天開

He can't really think we're going to finish the job today, can he? What planet is he on? 他不是認為我們今天能把工作做完吧?真是異想天開.

Throw the baby out with the bath water: 把嬰兒和洗澡水一起倒掉,把精華和糟粕一起丟掉

To lose sth that you want at the same time as you are trying to get rid of sth you do not want

It's stupid to say that the old system of management was all bad; there were some good things about it. The baby was thrown out with the bathwater.說舊的管理體制一無是處并不明智,它也有好的地方.那樣說就相當于把精華和糟粕一同丟棄.

Throw in the towel/sponge: stop doing sth because you know you cannot succeed; admit defeat 放棄,認輸,承認失敗

It's a bit early to throw in the towel—you've only just started the job. 現在放棄為時尚早---你才剛剛開始這項工作.

這個習語源于拳擊比賽:拳擊手將毛巾或海綿扔下即表示認輸.

This idiom comes from boxing: throwing in the towel or sponge is a sign that a fighter accepts defeat.