once做一旦,就,的意思的時(shí)候,是連詞,不是介詞,所以不能跟上動(dòng)詞的ing形式conj.一旦…就…Once you begin, you must continue.一旦開(kāi)了頭, 你就應(yīng)當(dāng)繼續(xù)下去. 句子應(yīng)該是： the samples can be...onceD.J.[wʌns]K.K.[wʌns]adv.一次I have been there once.我到過(guò)那兒一次。曾經(jīng), 昔時(shí)I once went around the world.過(guò)去我周游過(guò)全球。 conj.一旦…就…Once you begin, you must continue.一旦開(kāi)了頭, 你就應(yīng)當(dāng)繼續(xù)下去。can be sent是可以發(fā)出will be sent是將發(fā)出 看你想表達(dá)哪個(gè)意思都用sent好象重復(fù)了不好啊the tracking number will begiven to you after the samples sent