题目

根据短文内容，从各题所给的四个选项中选择一个最佳答案。A college student stayed up all night studying for his zoology(动物学) test the next day. The following morning, ______ he entered the classroom, he saw ten birds on the desks. Each bird was ______ with a sack(麻布袋) and only the legs were outside.The teacher told the students that the test would be to watch each pair of bird legs and write down the name and the living habits of each bird.The student looked at each pair of bird legs. ______ of them looked the same to him. He began to get upset. He stayed up一张长30厘米，宽18厘米的长方形硬纸板，在它的四个角各剪去边长6cm的正方形，折成一个无盖的纸盒。这个纸盒用了多少铁皮？容积有多少？