英语造句中什么时候会出现“be”这个单词，放在什么位置？

I won't be free this afternoon. I'll be seeing a friend off.我今天下午没空,我要给朋友送行。What were you doing from 9 to 11 this morning?今天上午九点到十一点你在做什么?He is working.他在工作。2.(与及物动词的过去分词连用,构成被动语态)被...The problem was solved long ...