________ of the two castles were built many years ago.

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I'm a stamp collector. I've got ________ stamps at home.

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There are only twenty students in the classroom, ________ are all playing basketball on the playground.

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The new boy introduced ________ first and then joined us.

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Less meat protects us ________ too fat.

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Our class teacher, together with all her students, ________ table tennis every afternoon.

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You haven't had a rest for thirteen hours. You ________ be very tired.

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Water pollution has made our rivers and lakes ________ very dirty.

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Don't forget ________ the lights when you leave home.

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