Usage and Grammar

Q. Several times lately I’ve written or revised copy to change the word in the prepositional phrase following “kinds of” or “types of” to the singular from the plural—from “what kinds of cats?” “three types of errors” to “what kinds of cat,” “three types of error.” And several times a client has treated the resulting phrase like an error. I haven’t found the answer to this usage question in CMOS. What do you think?

A. Your client is right. According to Webster’s, “kinds of” takes a plural if the relevant noun is countable. (Dictionaries are good for this kind of question.)