下列变化中，属于化学变化的是（ ） A．干冰升华 B．木条燃烧 C．活性炭吸收异

用方框中所给单词的适当形式填空，使短文通顺、正确、连贯（每个单词限用一次）.

deep     watch   or   school   other   something   accident   few   happen   from

School is where we learn, make friends and grow up. But ____小题1:___ happen daily in schools across the world. We hear reports of students falling down ____小题2:___ buildings while cleaning windows. Other students are hit by football on the playground. Three years ago, some students fell down on the stairs and were stepped on by __小题3:____, with tragic results.
We feel ____小题4:___ sorry for the loss of lives. There is ___小题5:____ we can do to bring the students back, but we can try to prevent (防止) such things from ____小题6:____ again. You should do the following things to prevent a stampede (踩踏)。
After class or school, don’t rush out at the same time. Wait until there are ___小题7:____ people trying to leave.
When you walk with a crowd of people, stay alert (警惕的) and ____小题8:____ your steps. Don’t play around.
Be familiar with your ___小题9:__ and learn where the safety exits are.
When there’s pushing and squeezing (挤)， don’t move and try to hold on to something. ___小题10:__ stay in a corner until the crowd leaves.