''these'' or ''this'' trousers/pants ? what's their plural and singular?
singular: I like these/this trousers.
plural: I want two of these trousers. (I think)

Question

Answer

singular : I like this PAIR of trousers
singular : I like these trousers
plural : i like these 2 PAIRS of trousers or these 2 trousers

Answer

singular: I like these trousers.
plural: I want two of these trousers.

Here are twelve more words that are always plural
http://blog.oxforddictionaries.com/2015/05/12-nouns-that-are-always-plurals/