(at) the instant
一…就…as soon as
He came the instant I called his name.我刚一叫他的名字,他就来了。
At the instant I saw him I knew he was the man the police were looking for.我一看到他就认出他正是警方在寻找的那个人。
not for an instant
根本不not at all
Not for an instant did I believe he had lied.我根本就不相信他撒了谎。
this instant
立即,马上immediately
If you don't leave this instant,I will scream.你要是不马上离开,我就喊了。