有孔毛细血管区别于连续毛细血管的主要特点是（） A.内皮细胞是连续的 B.胞质内含吞
题型：单项选择题 A1型题
问题：
有孔毛细血管区别于连续毛细血管的主要特点是（）
A.内皮细胞是连续的
B.胞质内含吞饮小泡较多
C.内皮细胞有许多贯穿细胞的孔
D.基膜薄而连续
E.通透性较小
题型：单项选择题 A1型题
阅读理解.
Besides calling 911,here is what to do in some lifethreatening emergencies when no one is
around to help.
Lost in the wilderness
First,you've got to acknowledge you're in trouble.Stay where you can be seen clearly and
remember to rest. Keeping a sense of humor helps too-it reduces stress and helps creative
thinking.In a wide open area,make a colorful cross out of rocks to show your present position.
Choking
Aim to hit the top of the chair against your stomach,in the soft part below the bony upsidedown
V of the ribs (肋骨)．Make a sudden push against the chair.If you still can't breathe after six
tries,call 911,even if you can't talk.Write the word choking somewhere nearby,and leave the line
open until help arrives.
Severe bleeding
Use your hand or clean cotton,or paper towels,or a scarf,or any cloth you can find,and push
down on the wound until the bleeding stops.But if you put a band around your leg tightly,you're
going to close the vessels(血管) to the entire leg.In this way,you could lose your foot.
Bear attack
If you surprise a bear,don't run away.That invites an attack.Instead,stand up and back
away slowly,without looking the bear in the eyes.If it does charge (猛冲) at you,stick out
your chest,raise your arms,and spread your legs.Shout at the bear,to frighten it.If it's going
to attack,lie facedown,with your hands held firmly behind your neck.Play dead until you're
sure the bear is gone.
1.When you see a colorful cross made of rocks in the wilderness,you know ________.
A．someone is bleeding
B．someone is choking
C．someone is lost
D．someone is attacked by a bear
2.If you are still choking after six tries，you should ________.
A．keep a sense of humor
B．call 911 and leave the line open
C．use your hand or clean cotton
D．lie down with your hands behind your neck
3.Don't tie around your bleeding leg tightly，or you could ________.
A．stop bleeding
B．reduce stress
C．lose your foot
D．cause breathlessness
4.The passage is mainly teaching us how to ________.
A．survive the emergencies
B．avoid a bear attack
C．deal with a choke
D．find our way