题目内容：
Directions：There are 20 blanks in the following passage．For each blank there are four choices marked[A]，[B]，[C]and[D] on the right side of the paper．You should choose the ONE that best fits into the passage．Then mark the corresponding letter on Answer Sheet 2 with a single line through the center．
根据以上短文，回答题
请作答______
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