Short is that letter, in which adding two letters make it shorter
Add one letter to each word below - anywhere in the word - so that each numbered pair becomes two words of opposite meaning. For example, adding P and L to PLUM and SENDER would result in PLUMP and SLENDER.
Can you find an English word which is singular, but when you add an "s", it becomes plural and when you add another "s" it becomes singular again?
