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【单选题】
在“观察叶绿体”的实验设计中,选择的实验材料必须是绿色植物的叶肉部分,使用的实验手段必须是显微镜的高倍镜,有可能成功。这反映了实验设计的 原则A.
可行性
B.
对照性
C.
控制性原则
D.
安全性原则
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举一反三
【单选题】质量为2kg的物体做自由落体运动，经过2s落地。取g=10m/s 2 。关于重力做功的功率，下列说法正确的是（）
A.
下落过程中重力的平均功率是400W
B.
下落过程中重力的平均功率是100W
C.
落地前的瞬间重力的瞬时功率是400W
D.
落地前的瞬间重力的瞬时功率是200W
【单选题】患者,女性,13岁,反复发作呼气性呼吸困难3年,引起呼气性呼吸困难最常见的病因是
A.
支气管异物
B.
大支气管肿瘤
C.
大片肺组织实变
D.
大量胸腔积液
E.
小支气管痉挛
【简答题】A boy and a girl were a couple of lovers. The girl liked feeling rain, so the boy was always holding the umbrella when it rained and most part of the umbrella was over the girl. Rain showered the boy ...
【多选题】The young boy makes me giggle.2. The faces he makes when he talks are so funny.3. The writers wanted to show how kids think.4. The boy always talks in funny rhymes and uses made-up words.5. The show i...
A.
Why is the boy funny?
B.
How would you describe the show?
C.
Why did the writers create the show?
D.
Who's funny?
E.
What kinds of funny things are said?
【简答题】The boy always with his parents' opinions. 这个男孩经常与父母的以及那不合。
【简答题】One day, a boy fought with one of his classmates. 小题1: “He is really bad and I hate him.” the boy said. The grandfather said, “Let me tell you a story. When I was a boy, I too, sometimes hated others...
【简答题】Complete the summary according to the text you have read. This is a story about a boy and an apple tree. When the boy was just a 1 —— , he and the tree used to play together. With time 2 —— ...
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