Transitional words and phrases fall into this category.

0I'm quoting from a certain grammar book:02br
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01b01i01font00Parenthetical Expression:02font02i02b02br
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01font00Use a comma to set off expressions which interrupt the flow of the sentence.02font02br
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01font00> If it were up to me, however, the trip would be cancelled.02font02br
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01font00> Mary Ann, as you know, has offered to baby-sit.02font02br
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01font00> Jackie, on the other hand, has refused to pitch in.02font02br
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01font00Transitional words and phrases fall into this category.02font02br
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01font00What are 01i00transitional words and phrases02i00?02font0-