make hay while the sun shines; strike while the iron is hot ? 常言說，“～”，你怎么能這么猶豫不決呢？ As the saying goes，“Strike while the iron is hot.” How can you shilly-shally like this?
時不可失shí bù kě shī
時：時機；失：失去。緊緊抓住有利時機，不可錯過。there is no time to lose, strike while the iron is hot, Now for it!