问题 单项选择题

图示体系是几何()的体系。

 

A.不变

B.不变且无多余约束

C.瞬变

D.不变,有一个多余约束

答案

参考答案:B

解析:

将大地视为一个刚片,三个刚片分别用三个铰两两相连,铰(1.2)和(1.3)在无限远处,它们与铰(2.3)不会在一直线上

[*]

写作题
书面表达。
     根据中文提示和英文内容,写出意思连贯、符合逻辑、不少于60词的短文。 请不要写出你的校名
和姓名。
     请你阅读下面有关奥运冠军费尔普斯的文章节选部分,然后以中学生李华的名义给费尔普斯写一
封信,简述他的行为和你的看法,然后给他提出有效缓解压力的建议。 
                                               Phelps Apologizes to Fans
      Olympic champion Michael Phelps has apologized (道歉) to Chinese fans on the Internet for
taking marijuana, a kind of drug.
     "As many of you know, I recently did something that was not what people expect from me."
Phelps said, with his words printed in Chinese.
     "The past few days have been hard for me, but I've received support and encouragement
 online from so many Chinese friends."
Dear Phelps,
      I am Li Hua, a middle school student from Beijing. _______________________________________
____________________________________________________________________________________
____________________________________________________________________________________
                                                                                                                                Best wishes,
                                                                                                                                   Li Hua
单项选择题