desk桌子不是可数名词，desk是桌子，而不是椅子；
可以说some desks 一些桌子；
some desk 某张桌子；
复数 desks
I always leave a clear desk at the end of the day.
每天工作结束时，我总是把桌上收拾干净不放任何东西。
The paper had fallen down between the desk and the wall.
那张纸掉在桌子和墙壁之间的缝隙里。
That desk takes up too much space.
那张桌子占的地方太大。
