原式=3×6×22•2-1=62-1=2．
Only when you are old enough ________ that you didn't make most of your time. [ ]
A. you will realize
B. will you realize
C. have you realized
D. do you realize
A．E=Bav，
B．E=NBav，
C．E=Bav，
D．E=NBav，
