opportunist

机会主义者、投机者、投机取巧的人贬义

He is an opportunist who changes sides whenever it suits him.

他是个机会主义者，只要对自己有利就换边站。

善于把握机会的人多用于运动报导

The striker is a natural opportunist in front of goal.

这名前锋在门前总能把握住机会。

投机的、机会主义的贬义

Critics called the policy an opportunist move before the election.

批评者称这项政策是选前的投机之举。

伺机而动的、临时起意的多指犯罪

Police believe it was an opportunist theft, not a planned one.

警方认为那是临时起意的窃案，而非事先计划。