1.A
关系代词that代替先行词The road,在定语从句 __ leads to the temple中充当主语.
2.D
关系代词whose= the writer's.
3.B
关系代词who代替先行词a boy,在定语从句中充当主语.
4.A
关系代词whom代替先行词The three students在定语从句中充当taught的宾语.
5.C
关系代词which代替先行词the letter,做定语从句的主语.
6.C
关系副词why = for which = for the reason（先行词）
7.D
belong to which = belong to a/the society
8.C
where = in which = in the place
9.B
when = on which = on the day
10.A
that代替先行词the music,在定语从句中充当heard的宾语.
由于先行词被最高级the most beautiful修饰,只能用that不能用which.