伺机而动

nà míng qiāng shǒu miáo zhǔn le tā sì jī ér dòng

那名枪手瞄准了他，伺机而动。

The gunman aimed at him, waiting for an opportunity.

rén men bì xū líng huó yìng biàn sì jī ér dòng cái néng qǔ dé jìn zhǎn

人们必须灵活应变，伺机而动，才能取得进展。

One needs to be adaptable and opportunistic to make progress.