"Paper is used for writing on "or "paper is used for writing",which one is grammatically correct ?
Chopstics are used for eating . Chopstics are used for eaing with.
This desk is used for putting the computer. This desk is used for putting the computer on.
Of two pairs of sentences, which one is correct in each? As per wikipedia, which gives a brief introducion about paper--Paper, a thin unwoven material made from milled plant fibers, is primarily used for writing, artwork, and packaging. Here "used for writing" , but not "writing on".
However in an English textbook for Junior Three students in China, when it comes to the usage of some objects, an example--"paper is used for writing on"-- is given. So I want to know when a prep., after a verb. in such a sentence structure, can be omitted. Why is it OK that " It ( the lock )is used for locking the door" (also an example in the textbook), but why not " it is used for locking the door with"?