불가산 명사 Uncountable nouns
<단어만 쓰면 무조건 단수. 단어에 단위를 붙이면 복수로 사용 가능하다>
I have a lot of grammar to memorize by tomorrow.
He has an expansive vocabulary.
I still have five homework assignments to make up.
He provided us with a wealth of information on the subjecct.
Thanks for that piece of advice!
He has extensive knowledge in that field.