这几个句子其实主要是老师向考察你是否注意诸位搭配的一致,所以翻译上大可不必复杂,请参考: what's on the desk? what are on the desk? There is a pen and a pencil on the desk. There is a desk and a bed in my bedroom. 加油
什么东西在桌子上? What is on the desk? 有哪些东西在桌子上? What kind of things are on the desk? 有钢笔和铅笔在桌子上. There are a pen and a pencil on the desk. 我房间里有书桌和床. There are a writting desk and a bed in my room.