A.①②③④⑤ | B.①⑤③④② | C.④③⑤①② | D.②④③⑤① |
A.养料增多,颜色由鲜红变成暗红 |
B.废物增多,颜色由暗红变成鲜红 |
C.氧气增多,颜色由暗红变成鲜红 |
D.二氧化碳增多,颜色由暗红变成鲜红 |
A.一层 | B.两层 | C.三层 | D.四层 |
A.(1)(2)(3)(4)(5) | B.(1)(5)(3)(4)(2) | C.(4)(3)(5)(1)(2) | D.(2)(4)(3)(5)(1) |
A.肺泡外包围着丰富的毛细血管 |
B.肺泡壁是一层上皮细胞 |
C.毛细血管壁也是一层上皮细胞 |
D.肺泡壁是由软骨支撑 |
© 2017-2019 超级试练试题库,All Rights Reserved.