According to the author, eyewitness testimony is______.
A. always a reliable evidence
B. the most convincing evidence
C. sometimes a distortion of people's perception
D. a simple recording of visual input
What purpose does this passage possibly serve？
A company introduction to its employees.
B. A market analysis for a specific industry to inform. a client.
C. An annual report of a company to direct its future decision.
D. A marketing strategy proposal for discussion.
听力原文：Where does John first recommend？
(24)
A. Library.
Bookstore.
Computer.
D. Tutor's office.
若梁的受力情况对于梁的中央截面为反对称(如图)，则下列结论中正确的是()。
A. Q图和M图均为反对称，中央截面上剪力为零
B. Q图和M图均为正对称，中央截面上弯矩为零
C. Q图反对称，M图正对称，中央截面上剪力为零
D. Q图正对称，M图反对称，中央截面上弯矩为零
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