Here are the sentences with the verbs in brackets filled in with the correct tense:

1. My uncle **moved** to Da Lat in 2005. (Past Simple)
2. The Greens **have been** to many countries in the world so far. (Present Perfect)
3. We **went** to that village to do volunteer work several times. (Past Simple)
4. We **spent** our summer vacation in Ha Long Bay last July. (Past Simple)
5. Our teacher **has explained** to us how to use the printer already. (Present Perfect)
6. The postman **delivered** the letter half an hour ago. (Past Simple)
7. Mai **has not finished** her homework yet. (Present Perfect)
8. I **have visited** our form teacher in the hospital already. (Present Perfect)
9. I **heard** the good news from Mary a few minutes ago. (Past Simple)
10. They **have not started** the project yet. (Present Perfect)