1.He' s on to us. "on to "＂意识到sth，明白了sth的本质＂

eg: The police were on to the criminals' plan very quickly. 警察很快了解了犯罪分子的计划．

If anyone' s on to us we should call the whole thing off. 要是有人知道了我们就得取消．

2.A new position for me in his company. "position" ＂工作，职位＂

eg: I' m currently looking for a position somewhere new. 我最近正在别的地方寻找一个新工作．

Then' ve offered me a position starting next January. 他们给了我一个新工作，明年一月份开始．

3.In a heartbeat. 马上，立刻，

eg: I' d leave in a heartbeat if I had any money. 要是有钱我马上就离开．

I' ll arrive in a heartbeat. 我马上就到．