在2、4、6、8、10、12中,中位数是( ),平均数是( )。
7;7
After the class,the students went out of the classroom one by one, but only Mary______.
A.left
B.hadleft
C.wasleaving
D.wasleft
水磨石地面面层的厚度在正常情况下宜为( )。
A.2~5mm B.5~12mm C.12~18mm D.18~25mm