求助几道英语题目（定语从句）

求助几道英语题目（定语从句）
1.I will never forget the days _______ we spent together.
A.which B.when C.where D.whose
2.I was given these books on cooking,the first___ I really enjoyed.
A.of that B.of which C.that D.which
3.---Do you have anything to say for yourselves?
----Yes,there's one point ___ we must insist on.
A.why B.where C.how D./
4.Don't get too close to the house,the roof___is under repair.
A.whose B.which C.of which D.that
5.Maths is a subject ___ people learn for practical use.
A.where B.when C./ D.why
ABCD