用括号中所给词的适当形式填空。(2.5分)

小题1:What ________ you _______ ( do ) from eight to ten yesterday morning ?

小题2: The music_________ ( sound ) great .

小题3:Would you mind ______________ ( not smoke ) here ?

小题4:They learned Japanese by ________( they ) last year .

小题5:Several _________( science ) took part in the important meeting yesterday .

X线片上密度最高的组织是（）

A.釉质

B.牙本质

C.牙骨质

D.牙髓

E.牙槽骨