正确答案: D

地球化学循环

题目：时间长、范围广、闭合式的循环是（ ）

解析：D

查看原题

举一反三的答案和解析：

[单选题]引起病理性浊音和实音的原因不包括 （ ）

气胸

[单选题]Passage FiveIn the 1900's, American townspeople usually washed and brushed their teeth and combed their hair in the kitchen. Or they kept a water pitcher (大水罐) and a wash basin in their rooms and took care of these things there.

kept and used

解析：51．答案为D。根据第一段最后一句，Or they kept a water pitcher and a wash basin in their rooms and took care of these things there作出该项选择。