肛管的下界为（），上界为（）。
参考答案：肛门缘；齿线
_________ you like this bicycle?[ ]
A. are
B. Are
C. do
D. Do
Can you imagine what life will be like in ______ time? [ ]
A. 50 years'
B. 50 year's
C. 50-years'
D. 50-years
