Biến đổi giữa PAST SIMPLE – PRESENT PERFECT:
. 2. He hasn’t smoked cigarettes for a month. => The last time
3. I started working as a volunteerin 2015. => I have
4. My mother has done charitable work for five years. => My mother began
5. This is the first time they’ve been to Korea. => They haven’t
6. The last time I saw my uncle was two years ago. => I haven’t
7. Peter has never seen that film before. => This is the first time
8. She started doing volunteer work five years ago. => She has
9. This is the first time I have been to a soccer match. => I have
10. How long have they lived here? => When did