题目

 —Does your uncle still smoke? —He       given it up. It’s two years ever since he      . A. can’t have; smoked                    B. may have; smoked C. should have; has smoked               D. should have; didn’t smoke 答案：B15．某同学在学习完运动系统的组成后，决定利用圆规和弹力布制作骨骼肌牵动骨运动的模型，在他设计的四种模型中，你认为最合理的是（　　）A．B．C．D．