“
Don't get too close to the house ___ roof is under repair.
a.whose
b.which
c.of which
whose也可以用于物吗？

当然`whose=介词+which`代人代物均可
There is a book there whose(=of which) cover is blue.
There is a man there whose(=of which) eyes are blue.
”
书上说whose不等于of which啊,用of which的话后面的名词要加上冠词
哪个对?

whose可以用于物. 它代表所有第三人称所有, 包括his/her/its

关于冠词
the house whose roof > the house's roof, "the house's" 已经是冠词了, 再加就重复了. the house's the roof 显然是错的
the house of which the roof > the roof of the house, 这里要加冠词, 因为roof没有别的冠词. roof of the house显然缺少冠词