jiāo juǎn
zhuī jiū
tuī mén
lǚ yóu
____
如图，AD是△ABC的中线，∠ADC=60°，点C′与点C关于直线AD对称，若BC=6cm，则点B与点C′之间的距离为____ cm．
找出下列各图形中数的规律，以此类推，a的值为____．
It is he , rather than I, that in the company for two years.
