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spy on

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Secretly or furtively observe someone or something, as in The children loved spying on the grownups, or The company sent him to spy on the competitor's sales force. [Early 1600s]

QUIZ
GOOSES. GEESES. I WANT THIS QUIZ ON PLURAL NOUNS!
Test how much you really know about regular and irregular plural nouns with this quiz.
Question 1 of 9
Which of the following nouns has an irregular plural form?
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.

How to use spy on in a sentence

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