图1-23梁的支座反力为（）。
A．1/4
B．1/2
C．3/4
D．1
参考答案：A
To some students, they ______ study higher maths (高等数学) at school. It has never been of any use in
their daily lives. [ ]
A. need not to
B. mustn't
C. needn't to
D. don't need to
人脑产生想象的基础材料是（）
A.感觉
B.知觉
C.表象
D.记忆
