You almost never use aback on its own. The living phrase is taken aback, which means suddenly very surprised or shocked — so surprised that for a second you stop, as if someone has pushed you backwards. It is a little bookish, but news writers and careful speakers still use it.

You almost never use aback on its own你幾乎不會單獨用aback這個字。The living phrase is taken aback現在還在用的說法是taken aback which means suddenly very surprised or shocked意思是突然非常驚訝或震驚 — so surprised that for a second you stop——驚訝到你愣了一下 as if someone has pushed you backwards好像有人把你往後推了一下。It is a little bookish這個說法有點書面 but news writers and careful speakers still use it但新聞寫作和講究用字的人還是會用。

It often comes with by: taken aback by the news, by her answer, by how blunt he was. The feeling is not mild surprise; it is the kind that makes you blink.

It often comes with by它常常跟by一起用: taken aback by the news, by her answer, by how blunt he was像taken aback by the news（被這消息嚇一跳）、by her answer（被她的回答嚇一跳）、by how blunt he was（被他的直白嚇一跳）。The feeling is not mild surprise這種感覺不是輕微的驚訝 it is the kind that makes you blink是那種會讓你愣一下、眨眨眼的驚訝。

The picture behind the phrase is from sailing: if the wind hits the sails from the front, the ship is taken aback and thrown off its course. People then used that picture for a person thrown off balance by news or a remark.

The picture behind the phrase is from sailing這個說法背後的畫面來自航海: if the wind hits the sails from the front如果風從正面吹向帆 the ship is taken aback and thrown off its course船就會被taken aback，偏離航道。People then used that picture for a person thrown off balance by news or a remark後來大家就用這個畫面，形容一個人被消息或一句話打得措手不及。

You would not say I abacked or I was aback; the shape is be taken aback.

You would not say I abacked or I was aback你不會說『I abacked』或『I was aback』 the shape is be taken aback固定的用法是be taken aback。