1. the official language 2. join a basketball team 3. take part in/ join in a basketball match 4. A friend of theirs is playing chess. One of their friends is playing chess. 5. He doesn’t feel well (adj.) today.
6. The house has been on fire for five minutes. 7. It’s a 150-square-metre flat. = The flat is 150 square metres. 8. The suitcase is so heavy that I can’t carry it. 9. The suitcase is not light enough for me to carry. 10. He is taller than any other boy in our class.