This pdf file from Auburn Montgomery College in Alabama is a great resource for students trying to learn to avoid shifts in person.  Clear instruction and numerous sentence and paragraph level exercises.

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An excellent and very thorough handout on passive voice—when it is Ok to use the passive voice, and when it is best to avoid it.  Also includes a discussion of passive voice used in different writing situations.  Well worth reading!

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Very thorough discussion of how to maintain verb tense consistency in narrative and other kinds of writing. The discussion of active and passive voice is less extensive, but good.  Both pages include links to exercises.

Verb Tense Consistency

Active and Passive Voice

Another great podcast from Grammar Girl.  Good explanation of when to use passive voice and when to avoid it.  The site includes transcripts of all podcasts.

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