主要想到四个，如下：

1. immediately用作连词可以表示“一……就”：

Immediately he came I told him the news. 他一来我就把消息告诉了他。

I recognized her immediately I saw her. 我一看见她就立刻认出她来了。

I'll call you immediately I hear anything. 我一有什么消息就给你打电话。

2. directly用作连词可以表示“一……就”：

Directly he was paid, he went out shopping. 他刚一领到钱就出去购物了。

I came directly I heard what had happened. 我一听说发生的事就赶来了。

I went home directly I had finished work. 我一干完活就回家了。

3. instantly用作连词可以表示“一……就”：

Tell me instantly he arrives. 他一到就告诉我。

I recognized her instantly she entered the room. 她一走进房间，我就认出了她。

He ran across the grass instantly he perceived his mother. 他一看到母亲，就跑过了草地。

4. once 用作连词可以表示“一……就”：

Once she spoke, I recognized her. 她一开口我就认出了她。

The water is fine once you're in! 你一旦下了水，就会觉得水里挺舒适。

Remember that you won't be able to cancel the contract once you've signed. 记住一旦你签了字就不能取消合约了。