at once 是什麼時態

A computer can perform many tasks at once.

電腦能同時做多項工作。

She fell in with my idea at once.

她立刻同意了我的主意。

We have several projects all on the boil at once.

我們熱火朝天地同時上馬了幾個項目。

It is a physical impossibility to be in two places at once.

同時身處兩地在自然法則上是不可能的'。

He couldn't reasonably be expected to pay back the loan all at once.

公平合理地講，不可能指望他一下子歸還全部借款。

The award-winning novelist often has three or four books on the go at once.

那位獲獎小説家經常是三四部小説同時寫的。