两封信随机地投入标号为1，2，3，4的4个邮筒，则1，2号邮筒各有

【名词&注释】

甲状腺下动脉(inferior thyroid artery)、两封信(two letters)

[单选题]两封信随机地投入标号为1，2，3，4的4个邮筒，则1，2号邮筒各有一封信的概率．等于

A. 1/16
B. 1/12
C. 1/8
D. 1/4

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学习资料：

[单选题]We can conclude from this passage that avalanches________

回答下面的题目Never laugh at a snow covered mountain! Laughter and yelling, during the avalanche season, can cause a deadly pile of snow．Huge snow slides are most common in mountains where there are steep slopes that are well buried in snow and ice．The snow builds up slowly and lands very softly．This can create a very touchy, unstable situation．Tons of snow may be held up by only the friction between snowflakes．The deep snow is like a house of cards．The slightest movement can cause it to fall．As soon as something slips, this great mass of snow will come crashing down the mountainside．Slides may be started by sound vibrations．They may also be started by the weight of wet, melting snow．Once an avalanche has been triggered, the cause no longer matters．Moving down a steep slope, it picks up great speed and added snow．Some avalanches travel as fast as two hundred miles per hour．The force of an avalanche will mow down anything in its path．Whole houses have been swallowed up by these fast-paced piles of snow．The wind that is caused by an avalanche is almost as destructive as the snow itself．Winds from an avalanche have been known to travel as fast as those of a tornado．So, when approaching a thickly snow covered mountain, speak softly!Avalanches can be started by________

A. are common everywhere
B. are not very common
C. have killed people
D. are a thing of the past

[单选题]__________

根据以下内容，回答下面的题目。The death of a child, _51_ one’s own child,is something the mind can hardly comprehend．It seems togo _52_ nature．The end of a life that is still forming_53_ has just begun is an almost unthinkable cruelty．But it happens．Parents sometimes must witness the illness and death of the children_54_ whom they gave birth．And _55_ will ever fill theempty place that the dead child leaves behind．Parents_56_ to die before their children, which is the natural order of life events．When the situation is reversed and a child dies _57_ the parents itseems wrong．Yet we never know why one person dies andanother lives．But we do know _58_ a child is gone, theparents still have a future, as grey and worthless as it may at first seem．Death may take the child, but the love never _59_．The sorrow after a child’s death is one ofthe longest and hardest type of _60_ to live with．And ittakes long to deal with the parents’ own emotions．__________

A. think
B. expect
C. like
D. surely

[多选题]颈外动脉发出的分支有 （　　）

A. 面动脉
B. 舌动脉
C. 甲状腺下动脉
D. 脑膜中动脉
E. 颞浅动脉

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