Here are the completed sentences:

1. Scientists **not found** a cure for cancer yet?
2. They **have not discovered** a cure for cancer yet.
3. After he **took** antibiotics for five days, his sore throat **got** better.
4. Nam **has built** muscles since he **started** working out at the gym. He looks really fit now.
5. Susan really loves that film. She **has seen** it eight times!
6. The virus **has spread** very quickly in the last few weeks, and we need to control it now.
7. I **bought** all the ingredients. Can you help me cook the dish now?
8. As an avid traveler, I **have traveled** to more than 30 countries and 4 continents up to now.
9. I **have not slept** well just lately. I don’t know how to keep balance between work and play.
10. What time **did you get up** this morning?