科学家们将男人、女人体细胞内的染色体进行整理，形成了下列的排序图．请分析回答：

野兔主要以草的茎、叶为食，野兔体内与消化植物性食物相适应的结构是（　　）

判断下列句子是否正确,正确的写“正确”,错误的写“错误”

    The school library opening time is from 8: 00 to 16: 00. Students must remember （记住）that they must not bring food and drinks into the library. They can take out six books every time. And they can only keep them for one week. If they don't give back the books on time, they'll have to pay（支付） some money. Students must take care of all the books. But some books are only for teachers.

坐在岸边的小明同学看到河对岸的修桥工地上有工人用手匀速上下挥动铁锤，每隔1秒钟敲打钢轨一次．当铁锤碰到钢轨时，小明听到敲击声，而工人停止敲打以后，小明又听到了两次敲击声．如果空气中的声速为340米/秒，则河的宽度大约是