题目:在牛蛙的脊髓反射实验中,若要证明感受器是完成曲腿反射必不可少的环节,下列操作不合适的是
A. 环割后肢脚趾尖皮肤
B. 用探针破坏牛蛙的脊髓
C. 用0.5%HCl溶液刺激趾尖
D. 剪去牛蛙的脑
喵查答案:B
该实验是证明感受器是完成屈腿反射的必要环节,则感受器应为实验中的单一变量即感受器的有无,破坏牛蛙的脊髓无论有无感受器都不会发生屈腿反射。
……继续阅读 »
题目:在牛蛙的脊髓反射实验中,若要证明感受器是完成曲腿反射必不可少的环节,下列操作不合适的是
A. 环割后肢脚趾尖皮肤
B. 用探针破坏牛蛙的脊髓
C. 用0.5%HCl溶液刺激趾尖
D. 剪去牛蛙的脑
喵查答案:B
该实验是证明感受器是完成屈腿反射的必要环节,则感受器应为实验中的单一变量即感受器的有无,破坏牛蛙的脊髓无论有无感受器都不会发生屈腿反射。
……继续阅读 »
题目:_____you may have, you should gather your courage to face the challenge.
A. However a serious problem
B. What a serious problem
C. However serious a problem
D. What serious a pr……继续阅读 »
题目:The author thinks that with full government funding
A. teachers are less satisfied
B. students are more demanding
C. students will become more competent
D. teachers will spend l……继续阅读 »
题目:(C)
237 West Palmdale Boulevard
Fresno , Califormia93706
AmToy Corporation
Suite 15
TransAm Building
November 20, 2008
Dear Sirs,
As a concerned parent, I am writing to protest ……继续阅读 »