光明中学初一级有x人,初二级人数比初一级的3倍要少100人,则光明中学初一和初二级共有( )人。
4x-100
She had just finished her homework ______ her mother asked her to practise playing the piano yesterday.
A.when
B.while
C.after
D.since
去年,和羊毛的批发价不同,棉花的批发价大幅度下跌。因此,虽然目前商店中棉织品的零售价还没下跌,但它肯定会下跌。以下哪项如果为真,最能削弱上述论证?()
A.去年由于引进新的工艺,棉织品的生产加工成本普遍上升
B.去年,羊毛批发价的上涨幅度,小于棉花批发价的下跌幅度
C.棉织品比羊毛制品更受消费者的欢迎
D.零售价的变动一般都滞后于批发价的变动