室温下，一种气态烷烃和一种气态烯烃的混合物9克，其密度是相同_爱下问搜题

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问题选择题

室温下，一种气态烷烃和一种气态烯烃的混合物9克，其密度是相同条件下H₂密度的11.25倍．当混合物通过足量的溴水时，溴水增重4.2克，则这两种气态烃是（）

A．C₂H₆和C₂H₄

B．CH₄和C₃H₆

C．CH₄和C₂H₄

D．CH₄和C₄H₈

答案

答案：B

单项选择题

以下不符合化脓性脑膜炎脑脊液特点的是()。

A．压力增高

B．白细胞数明显增多

C．外观混浊

D．白细胞分类以中性粒细胞为主

E．蛋白质降低，糖和氯化物升高

完形填空

第二节完形填空（共20小题；每小题1.5，满分30分）
阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）出可以填入空白的最佳选项，并在答题卡上将该项涂黑。
Wishing to encourage her young son's progress on the piano, a mother took the small boy to a Paderewski concert.After they were seated, the mother saw a friend in the audience and walked   36  the aisle(通道)to greet her. 37 the opportunity to explore the wonders of the concert hall, the little boy rose and   38 explored his way through a door   39  "NO ADMITTANCE."
  40  the house’s lights dimmed and the   41  was about to begin, the mother returned to her seat and discovered that her son was   42 . Suddenly, the curtains parted and spotlights focused   43  the impressive Steinway on stage.In   44 , the mother saw her little boy sitting at the keyboard, innocently(纯洁地)picking out "Twinkle, Twinkle Little Star."
At that moment, the great piano master   45  his entrance, quickly moved to the piano, and whispered in the boy's ear, "Don't   46 ." "Keep playing." Then leaning over, Paderewski reached down with his left   47  and began filling in a bass part. Soon his right arm reached around to the   48  side of the child and he   49  a running obbligato(伴奏).Together, the   50  master and the young novice(新手)transformed a   51 situation into a wonderfully creative   52 . The audience was mesmerized(迷倒).
That's the way it is with God. 53 we can finish on our own is hardly noteworthy. We try our best, but the 54  aren't exactly flowing music. But   55 the hand of the Master, our life's work truly can be beautiful.
小题1:.

A．fortunately

D．surprisingly

A．fanscinating

D．frightening

C．performance