Not until he failed the exam _______he had left hisbooks untouched

If man can’t live _______ harmony _______ nature, the balance will be destroyed

He told me his computer company was in great need of a capable leader, ______ with strong will as well as good humor

To see a young couple loving each other is；but to see an old couple loving each other is the bestsight of all

Jack has lots of ______. He can learn much from them and use them to mail letters.