1.I must make full use of the time ( )left to me and do as much as I can to make progress.
A which.B that.C there is.D when
the time 用 left to me 修饰,that 可以省去
I must make full use of the time (that )there is left to me 是定语从句.分成两句就容易理解了：I must make full use of the time.There is the time left to me
2.The building over there is a library ,( )is a department store .
A where.B west of which.C to the west of it.D in the west of which
D中有the,是不行的,the代表特指,既然前面已经指明了那里有座建筑,是个图书馆.已经有特定的了,也就是限定了那座建筑,所以后面不用特指,也就不用加the