be doing … when suddenly啥意思?还有although … still

be doing sth.when 可不可以用be doing,when be doing? 如何对be doing sth when造句 各举一个be+doing+while+be+doing和be+doing+when+did的例句,be最好为过去时 be doing … when suddenly啥意思?还有although … still 用be+doing +when be用be+doing +when be +about to do+when.be+On the point of doing +when.has just done +when +did..各造两个句子! 用be doing when do造5句 用when be doing/do/does句型造十个句子 用be doing when do造5句,是陈述句, 用be doing when do造5句,是陈述句, be on the point of doing sth.when...be on the point of doing sth.when...是固定句型, 帮忙用was/were doing .when ; be about to do.when;had just done.when造句, had juest done..when ,were/was doing..when,be about to do ..when 啥意思啊 When tomorrow turns in today,yesterday,and someday that no more important in your memory,we sudd be+doing when he _____something useful,he wasted his time drawing little pictures.a.must have done b.shall be doing c.should be doing d.should have been doing When tomorrow turns in today,yesterday,and someday that no more important in your memory,we sudd有谁帮我翻译下是什么意思呢 while doing 是一种省略主语+be的用法 那有没有when doing这种省略?请问