患者女，60岁，左下21和右下12缺失，左上3残根，已做根管治疗，余留牙健康，前牙舌

Cathy is taking notes of the grammatical rules in class at Sunshine School,where she_______English for a year.

A．studies

B．studied

C．is studying

D．has been studying

肺通气的原动力是（）。

A.气体分压大小

B.肺内压变化

C.胸廓的节律性呼吸运动

D.胸膜腔内压变化

E.肺本身的舒缩活动

颌面部最常见的感染途径是（）

A.血源性

B.损伤性

C.腺源性

D.牙源性

E.手术时不合理的操作

血细胞比容(hematocritHCT)

As a young man, he ________ many social activities and later _______ the Party.

A．took part in; joined

B．took part in ; joined in

C．joined in; took part in

D．joined; took part