Dialog Competition Suppose you are enjoying your tripto Mount Tai.Call your parents oryour friends to tell them somethingabout your trip. >Act out your conversations.

The use of “while"and "when"."“While”means"during the time that something ishappening" or"at the same time as sth. is
happening”.只用于指一个时间段（只能与延续性动词连用）,表示主句与从句动作同时发生。
“while”也可以作为名词来使用,表示“一段时间,一会儿”，如:for a while, after a while
D“When” means "at or during the time that...”.它既可指一个时间点，又可指一个时间段;可与延续性动词连用，也可与非延续性动词连用。