--- Have you gone over what the teacher taught in class?        

--- Not yet.

--- Better remember: ________.

A．Don’t count your chickens before they’re hatched

B．A bird in hand is worth two in the bush

C．Strike while the iron is hot

D．All roads lead to Rome

牙根相对较粗大者为（）

A.上颌中切牙

B.上颌侧切牙

C.下颌中切牙

D.下颌侧切牙

E.上颌尖牙