at once的音标：at once的英式发音音标为：[æt wʌns]at once的美式发音音标为：[æt wʌns]...

all at once的音标：all at once的英式发音音标为：[ɔ:l æt wʌns]all at once的美式发音音标为：[ɔl æt wʌns]...

adv.立即，一起，同时，立刻...

He took off at once and headed back to the motel.他立刻离开，回到汽车旅馆。Remove from the heat, add the parsley, toss and serve at once.端离炉子，加上欧芹，颠起翻面后就立刻上桌。I wrote back to Meudon at once to fix up a meeting.我马上给缪顿回信安排会面。...

突然，同时...

at once的近义词有：immediately, instantly, presently, directly, shortly, soon, at once, right away。下面这些副词或副词词组均有"立刻，马上"的含义：immediately：指做完一件事后，立即就做另一件事，中间一般没有明显的时间间隔。instantly：指恰恰就在此刻，一秒钟也没耽误。presently：指不久、即将。directly和immediat...

All at once, Mick's serious expression softened into a grin.米克严肃的表情一下子变成了笑脸。All at once there was someone knocking on the door.忽然有人敲门。I feel terribly sleepy all at once.我突然觉得特别困。...