单项选择题
He prefers American examples ______ British ones when he is comparing educational systems.
单项选择题 The teacher asked a difficult question, and finally Todd ______ with a good answer.
单项选择题 Important people don’t often have much free time because their work ______ all their time.
单项选择题 I’m very sorry to have ______ you with so many questions on such an occasion.