设圆x2+y2=1的一条切线与x轴、y轴分别交于A，B两点，则线段AB长度的最小值为（ ）。
2
Our math teacher ______ in our school for 20 years and he _____ here when he was 23 years old.
A．has taught, has come
B．taught, comes
C．taught, came
D．has taught, came
申办信用卡时需提供的收入证明的有（）。
A.最近一个月的个人所得税扣缴凭证复印件
B.最近三个月工资收入的银行卡对账单
C.单位盖章的收入证明原件
