The key answer of exercise 1

a)

1. where
2. which / that
3. whose
4. that / which
5. who
6. where
7. who
8. whose
9. where
10. which / that

b)

Sentence 4.

c)

1. they
2. he
3. there
4. it
5. her
6. there
7. it
8. it
9. them
10. it

d)

1. who plays the part of Jon Snow in Game of Thrones
2. where the Mona Lisa can be seen
3. which is in the Himalayas
4. which was opened in China in 2011
5. whose husband is a Spanish footballer
6. who helped hundreds of slaves to escape