X线片上显示为包绕牙根的，连续不断的高密度线条状影像（）

A.牙釉质

B.牙骨质

C.牙槽骨

D.牙周膜

E.骨硬板

All the classmates _____ in that match.

A．enjoy themselves

B．enjoy ourselves

C．enjoyed themselves

D．enjoyed yourselves