1, B        2, C         3, C           4, D            5, A
6, A        7, C         8, C           9, C            10, C
11, B      12, D       13, C         14, B           15, B
16, A      17, D       18, C         19, A           20, C
21, The bed in which I slept was very modern.
22, The pen which I bought is red.
23, They live in a house built 20 years ago.
24, It was the book that Hoa gave him.
25, It is on her birthday that she often receives alot of gifts.