In English we often create sentences with more than one word preceding and modifying a noun. For example, there may be multiple adjectives used to modify the noun (an old, rusty machine) , multiple nouns used to modify the noun (a DNA sequencing assay), or combinations of adverb-adjective (a very difficult experiment) or adjective-noun (a hot water bottle).
Here are some rules to keep in mind when using compound modifiers:
When two adjectives precede a noun and modify the noun in the same way (such as in "an old, rusty machine"), then the adjectives should be separated wtih commas.
When combinations of noun-noun, adjective-noun, or adverb-adjective are used before a noun (and the first element modifies the second, rather than the final noun), then the words are usually connected with a hyphen: a well-designed experiment, a best-selling album, a high-school teacher). One exception to this is when the adverb ends in -ly or is the word "very", in which case no hyphen is necessary: an extremely long book, a very smart woman).
Finally, when a noun is used as a modifier before a noun (a bicycle tire, a pencil lead), it is never plural, even when it refers to multiple things: a two-day conference, a ten-person lab.
With these rules in mind, take this quiz to test your ability to use compound modifiers correctly. In each case, type the correct answer in the space, making sure all the punctuation is correct.