Here are the sentences with the correct forms of the verbs filled in:

1. I can’t believe she **hasn’t booked** her flight for the summer vacation yet.
2. They **do** community service in their neighbourhood every June.
3. Mount Everest is the most challenging mountain I **have ever climbed**.
4. Last year, we **explored** the savanna of Africa on a jeep tour.
5. How many eco-tours **have** you **taken** for the past three years?
6. I hope my best friend and I **don’t argue** during our field trip.
7. Peter **injured** his hand while he **was attending** an army course.
8. The tour guide **helped** us a lot since we **arrived** in Paris.
9. My flight **is** tomorrow so at present I **am packing** my clothes.
10. Carla usually **visits** Australia in the summer, but she **never goes** snorkelling to see the coral reefs.
11. **Have you ever been** to Japan? – No, I **have not been** to Japan yet.
12. How long **has** (Mrs Grey) **taught** in this school? – She **started** teaching here two years ago.
13. She **had** a breakthrough in her research some years ago, and since then she **has been** very successful.