LMS基于（）理论。
A.层次分析理论
B.学习有意义理论
C.建构主义学习
D.交互学习理论
参考答案：C
—Can you tell me _______ to send this postcard to New York by airmail?
—Let me check. Oh, it's one dollar. [ ]
A. how long it takes
B. how much it costs
C. who can help me
D. if there's a post office
宽度和厚度为50㎜的角模板，其长度可分为（）三种。
A、600
B、900
C、1200
D、1500
