once一旦 引導什麼從句

The industry today is nothing to what it once was.

這一行業的現狀與昔日的盛況相比微不足道。

She's planning to return to work once the children start school.

她正計劃孩子一入學就恢復上班。

I'll run back over the procedure once again.

我將重新考慮這個程序。

It's a lot of information to absorb all at once.

要一下子消化這麼多資料，真是很難。

If necessary I can come at once.

如果有必要，我可以馬上來。