连词组句。

1. how, is, blue, T-shirt, much, this

   ________________________________________________________________

2. red, are, each, those, sweaters, 50 dollars

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3. you, like, small, do, bags, ones, or, big

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4. pants, are, these, black, how much

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5. what color, you, do, want

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To keep healthy, Professor Johnson ______ cycling as a regular form of exercise after he retired.

A．took up

B．caught on

C．carried out

D．made for