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． 注意：此部分试题请在答题卡2上作答。
阅读以上短文，回答题
请作答______
[A]object
[B]article
[C]substance
[D]category
参考答案：
答案解析：