Câu trả lời:
Ta có vận tốc truyền âm trong không khí là 340m/s.
Khoảng cách từ nơi mình đứng đến chỗ sét đánh nếu nghe thấy tiếng sét sau 3 giây là: s = v.t = 340.3 = 1020 (m) ≈ 1km
Điền đúng từ loại
I've always wanted to be an (1. entertain) ... but never did anything about it until I lost my iob last year. After a (2. converse) ... with my friend about the (3. bore) ... of office life, I decided not to look for another job in management, but to earn my living from giving (4.perform) ... at events like kids' parties. So I became a clown! I'm (5. current) ... doing 4 or 5 parties a week and I love it! I love seeing the (6. excite) ... on the kids' faces when I walk in the room. I try to have a lot of (7. vary) ... in my act, so I tell jokes - most of which the kids find (8. amuse) ... - and bend ballons into funny animals, do impersonations of (9. fame) ... people and generally keep the kids (10. act) ... involed for an hour or two. It's the perfect job for me!