这是一个Therebe句型.由于一句子中只能有一个主谓宾结构,所以后面只能用分词来补充说明,而不能用work.要用的话必须有一个连词,可以改成这样:

　　Therearetwohundreddoctorsandnursesandtheyareworkinghardinthehospital.

　　Therearetwohundreddoctorsandnursesworkinghardinthehospital这句话中workingworkinghardinthehospital是现在分词短语来修饰前面的doctorsandnurses.相当于一个定语从句,此句也可以改写成:

　　Therearetwohundreddoctorsandnurseswhoareworkinghardinthehospital.