A:∠1=∠5
B:∠2=∠4
C:∠3=∠4+∠5
D:∠B+∠1+∠2=180°
— As soon as we ________ there.
A.得数在12000左右
B.得数在10000左右
C.得数在9000左右
D.得数在8000左右