Here are the best answers to complete the text:
- B many
- A who
- C any
- B which
- A some
- B many
- A that
- A a lot of
- C where
- B many
So the completed text would read:
Recent studies say that there are now over 400 million mother-tongue speakers of English, but there are (1) many more people (2) who use English as a second language - around 500 million. However, estimates vary because there aren't (3) any official figures. English is still the main language in countries like Nigeria and Ghana, (4) which were once ex-British colonies. People need to use English in (5) some official situations, such as in the government and education. Why don't these countries use a local language instead? Because it's too difficult to choose between the (6) many other languages (7) that belong to the local people! It's difficult to know the number of second-language English speakers in these countries because (8) a lot of the ex-British colonies are in poor parts of the world, (9) where people often don't get an education. This means that only a small percentage of the local population can speak English really well, but (10) many can say a few words in English.