Ответ:
1) Native speakers, mother tongue
2) two foreign languages
3) billion
1. can
2. must
3. Can/May, can not/may not
4. can/may/is able to
5. can/will be able to
6. should
7. should/ought to/must/have to
8. could
10. should
1-cities
2-interest
3-sights
4-founded
5-exhibitions
6-worth
Nikita goes to school
Nikita studies very well
Nikita does not like apples
Nikita speaks on Italian very well
Nikita likes play football
Nikita enjoys watching tv