超声波洁牙机的使用方法不正确的是（） A.放稳支点 B.握笔式握持器械需稳而轻 C.

Besides calling 911, here is what to do in some life-threatening emergencies when no oneis 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 upside-down 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 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.
小题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

小题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 our clean cotton	D．lie down with your hands behind your neck

小题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

小题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