By the time I got home, my grandmother ____ the dinner and was watching TV.（　　）

A.so
B.or
C.for
D.but

A.19层住宅(层高3.0m)
B.医院
C.每层建筑面积小于1000㎡的商住楼
D.建筑高度超过50m的普通旅馆

A.by
B.in
C.at
D.on