答案：B
The group of trees provided some shade ______ the sun .
A．of
B．over
C． for
D．from
铸造胎支托凹制备时，其宽度应为前磨牙牙合面颊舌径的（）
A.1/2
B.1/3
C.1/4
D.3/4
E.2/3
