Page 485
485.1 To Separate Adjectives
Commas are used to separate two or more adjectives that equally modify the same noun.
Many intelligent, well-educated scientists think that one of Jupiter’s moons could harbor life.
Intelligent and well-educated are separated by a comma because they modify scientists equally.
Scientists believe this cold Jovian moon has a liquid ocean beneath its surface.
Cold and Jovian do not modify moon equally; therefore, no comma separates the adjectives.
Use these two tests to help you decide if adjectives modify equally. (Try them on the sentences above.)
- Switch the order of the adjectives; if the sentence is clear, the adjectives modify equally.
- Put the word and between the adjectives; if the sentence reads well, use a comma when and is taken out.