A:对顶角相等
B:射线AB与射线BA表示同一条射线
C:两点之间,直线最短
D:在同一平面内,不相交的两条线段必平行
We dislike people ______ talk much but never do anything.
My family has two dogs. One is white, and________ is black.
若一个太阳能热水器内装有100kg温度为20℃的水,阳光照射一天后,水温升高到80℃,则热水器内的水吸收了____ 的太阳能,这是通过 ____ 方式改变了水的内能.