根据中文提示写出单词或词组，使句意完整、正确。
Great changes have taken place in China in ______（最近的）years.
—How many boys are there in your class?
—Thirty, about sixty_____(百分之)of the students in our class.
—The water in the river is dirty.
—Government has passed_____ (法律) against water pollution.
He joined the______(军队) in 2000.
“The greenhouse effect”causes the level of the oceans to_____ (上升).