be about to do .... ..即将。。。。比be going to 要急迫。 We were about to start ,when it rained.我们正要出发，这时下雨了。 I was about to go out, when somenone telephoned.我正要出去的时候有人打电话了。原题的意思是他正要告诉我那个秘密的时候，突然有人拍了拍他的肩膀。when 引导的动作一般是瞬间动词，而while引导的是延续性动词。如； They were talking when the teacher came in. While they were talking the teacher...
