Mr.Li as well as two sons ( is ) already in the waiting room这括号里为什么不可以用has been啊 还有为什么用is本人英语不是很好啊,

基本同意前边的回答,详细解释下,第一个解答是个人观点,不能保证正确：
1）"has been already"这种顺序似乎不太正规,already是修饰某种动作的副词,一般在过去分词之前(have/has already done)或句末,所以此句真要用现在完成时的话应为：Mr.Li as well as two sons has already been in the waiting room./ Mr.Li as well as two sons has been in the waiting room already.
另外,个人认为这句不适于用现在完成时,already用于现在完成时一般是强调动作的完成（如：* She had already left when I phoned.我打电话时,她早已走了.* I've already seen that film.我已经看过那部电影了.）,所以,像这种表示状态的句子只要用一般现在时或一般过去时就能表达“已经”的意思,如：The teacher was already in the room when I arrived.我到的时候,老师已经在屋里了.
2）当两个名词或代词由as well as连接时,其谓语动词的单复数由as well as前面的主语决定,这是主谓一致的法则之一.举例：
The teacher as well as the students was reading in the library.这位老师和学生们一起在图书馆阅读.
The students as well as the teacher were reading in the library.学生们和这位老师一起在图书馆阅读.
遵循同样法则的还有：with,together with,except,but,like,rather than,more than,no less than,besides,including等,也就是说谓语动词的单复数不受这些词组的影响,这类短语只用作修饰语.
以上~建议好好研究下时态和主谓一致这部分的语法,有问题多问老师啊,以前班里都是一下课老师就被围住了（貌似走题了……