题目

Evdence has been found through years of study______children’s early sleeping problem likely to continue when they grow up. A.why     B.how     C.whether      D.that 答案：D一个苹果在阳光下看起来是红色，这是因为（ ）A．红光透过苹果B．苹果只吸收红光C．苹果只反射红光D．红光折射进苹果