leave things until the last moment ⇒ 平时要努力,靠临阵磨枪不行。 Píngshí yào nǔlì, kào lín zhèn mó qiāng bùxíng. → You should work hard all the time, and not leave everything until the last moment.
单枪匹马
single-handedly
荷枪实弹
armed ⇒ 荷枪实弹的警察在巡逻。 Hè qiāng shí dàn de jǐngchá zài xúnluó. → Armed police are on the beat.