Điền từ vào _ ( mỗi _ điền 1 chữ cái sao cho có nghĩa ) 
1. Do you always eat breakfast before _ _ _ _ _ _ to class?
2. Is swimming _ _ _ _ _ water very difficult?
3. Elephants _ _ _ _ sounds but humans can't hear it
4. Copenhagen is _ _ _ _ _ _ in the Denmark ( câu này mik thử biggest rồi nhưng sai )