The clerk hasn't slept because he has got a lot of work.

Here are the correct time expressions for each sentence:

1. The clerk hasn't slept because he has got a lot of work.
   • c) for 24 hours
2. My uncle has been a doctor at the city hospital.
   • d) for 5 years
3. Look! Mr. Cheefy is cooking fish.
   • d) at the moment
4. Pam and Hans went to a nice restaurant.
   • c) yesterday
5. I usually play basketball with my friends.
   • b) at weekends
6. The runner hasn't started the race.
   • c) yet
7. Mandy and her mother are going to buy this house.
   • b) soon
8. The tourist is looking at an antique statue.
   • a) right now
9. Mr. Fanny was watering the vegetables at 10.
   • c) yesterday
10. Mr. Peak has climbed the summit of Mount Fuji.
    • a) already
11. Fred and Sharon listened to music.
    • b) last night
12. Madam Curie is going to Paris.
    • a) next summer
13. Susan is busy opening her birthday presents.
    • a) at the moment
14. Thomas couldn't ride a bicycle well.
    • b) two years ago
15. Mr. Chilly goes skiing holiday.
    • c) every winter