Decide whether each sentence below is punctuated correctly. If the sentence needs additional commas, indicate where the commas should be placed. | Did you see the movie that I saw yesterday? | The sweater that I left at school was a gift from my mother. | We should not buy grapes which scientists say are poisonous to dogs.

The first two “that” clauses identify which movie and sweater are meant, so they are essential and do not need commas. In the last sentence, “which scientists say are poisonous to dogs” adds extra information about grapes, so place a comma after “grapes.” Do not add a comma after “say”; “are poisonous to dogs” completes what the scientists say.

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