党的过渡时期总路线所指的过渡时期是_________。
EachyearintheUnitedStates,manyblackteenagers_______ofschool,eitherbecausetheycannotkeepuportheyhavetoworktosupporttheirfamily.
He________methathedecidedtoleaveonMonday.
设平面区域,则D绕y轴旋转所成旋转体体积为_____
Becareful,_______you'llfalldown.
