1. in an instant : 马上;
2. on the instant : 马上;
形容词
1. I shall be back in an instant. 我马上就回来。
2. An instant later the explosion occurred. 一会儿之后,爆炸就发生了。
3. instant的意思
3. I sent you the news the instant (that) I heard it. 我一听到此消息,便通知你了。