牙槽骨的吸收程度为Ⅱ度，表示（）

A.牙槽骨吸收在牙根的颈1／3以内

B.牙槽骨吸收在牙根的颈1／2以内

C.牙槽骨吸收占根长2／3以上

D.牙槽骨吸收达根长的1／2

E.牙槽骨吸收达根长的1／3

---What does Tom’s uncle do?

---He is a teacher. He __________ physics at a school now.

A．will teach

B．has taught

C．teaches

D．taught