能够反映细胞膜具有选择透过性功能特点的实例有 ①渗透作用 ②细胞吸收膜外K+ ③
题型：选择题
问题：
能够反映细胞膜具有选择透过性功能特点的实例有
①渗透作用 ②细胞吸收膜外K+ ③变形虫的变形运动 ④唾液腺细胞分泌唾液淀粉酶 ⑤海带细胞内的I-浓度远远高于海水中的I-浓度 ⑥氧气透过细胞膜 [ ]
A．①③④
B．②④⑤
C．②⑤
D．②⑤⑥
题型：选择题
小题1:Probably most injuries happen to skaters’ wrists because ________.
A．few skaters wear wrist guards
B．The wrist is the most fragile body part
C．skaters often push out their hands when falling
D．skaters don’t know how to protect their wrists小题2:________ are the majority in the study.
A．Those who wore helmets
B．Those who wore wrist guards
C．Those who wore knee pads
D．Those who wore no protective gear小题3:To reduce injuries greatly, a skater should at least wear __________.
A．a helmet and elbow pads
B．wrist guards and knee pads
C．elbow pads and wrist guards
D．the whole set of protective gear小题4:This passage is most probably be found in __________.
A．a poster
B．science fiction
C．collection of choice stories
D．newspaper小题5:What was the main point of the study?
A．To encourage people to learn skating.
B．To advise skaters to wear safety pads.
C．To advertise for skating protective gear.
D．To introduce ways of protecting skaters.