----Don't smoke here, Dad. Smoking _____ in public places.
----Oh, sorry. I'll stop right now.
A:isn't allowed
B:aren't allowed
C:doesn't allow
已知椭圆:x24+y2b2=10<b<2,左右焦点分别为F1,F2,过F1的直线l交椭圆于A,B两点,若|BF2|+|AF2|的最大值为5,则b的值是____
与小肠吸收营养物质有关的特征是 ( )
世界是纷繁复杂的,存在着是是非非,判断是非的依据是( )
根据图中小磁针N极指向,标出磁体的N极和S极,并画出磁感线的方向。