You wouldn't have heard of it.你應該沒聽說過

hear of:聽說

I rejoice to hear of your promotion.

聽說你高升我非常高興。

相關短語：not hear of不答應(拒絕考慮)

I will not hear of you making a trip to that place.

我不允許你去那個地方旅行。

She said you wanted to turn something in?她說你有東西要上交

turn in:上繳

Only a few guns have been turned in so far.

時至今日只上繳了少數幾支槍。

We'll return it to you as soon as we can.我們會盡快把它還給你的

as soon as:一 ... 就

I'll write you as soon as I get there.

我一到那兒，就給你寫信。

Let us start as soon as he comes.

等他一來我們就動身。

詞義辨析：once，as soon as兩者均為從屬連詞，引導時間狀語從句，都表示主句的動作緊跟在從句的動作之后發生。

once除表時間外，還表示條件，一般譯作“一旦......就......”。

as soon as強調的只是時間，譯作“剛......就......”或“一......就......”。