The children followed into the living room.
A:walked before
B:walked behind
C:walked on
如果点G是△ABC的重心,连结AG并延长交对边BC于点D,那么S△BDG:S△BGA的值为( )
为测定“碱”样品(主要成分为含少量NaCl的Na2CO3)中Na2CO3的含量,某化学课外活动小组的同学进行了以下探究: