既能阻断β受体，又能阻断α受体的药物是（）
A.普萘洛尔
B.拉贝洛尔
C.阿替洛尔
D.酚妥拉明
E.哌唑嗪
参考答案：B
—Guess what. I've got a visa for Iceland this summer for a holiday.
—How nice! You ______ the very beautiful sights then.[ ]
A. have been enjoying
B. are enjoying
C. will be enjoying
D. will have enjoyed
关注气候变化，应对全球气候变暖等国际问题，越来越离不开中国的参与。
判断：（ ）
理由：
