△ABC的三边长分别为7、6、2，△DEF的两边分别为1、3，要使△ABC∽△DEF，则△DEF的第三边长为______．

. --- Believe it or not, I passed the driving test at the first attempt yesterday.

--- Great! But remember you can never be ___ careful when driving a car in the street.

A．enough

B．rather

C．quite

D．too