1. The doctor, ______ sounded the alarm about the virus, was regarded as a hero.
- A
A. who
- B
B. which
- C
C. where
- D
D. what
2. The train was crowded and I had to get into a carriage ______ already seven other people.
- A
A. when there were
- B
B. which there were
- C
C. that there were
- D
D. where there were
3. My friend, ______ you met at the exhibition, joined a campaign to help children.
- A
A. that
- B
B. which
- C
C. whom
- D
D. what
4. This book, ______ explores the meaning of love, is a bestseller of The New York Times.
- A
A. that
- B
B. when
- C
C. who
- D
D. which
5. I shall never forget those years ______ I lived with my grandpa, _____had a great impact on my life.
- A
A. that; which
- B
B. when; which
- C
C. which; that
- D
D. when; who