第14题: [单项选择]空心板较为经济的跨度为( )m。 A. 2.4~4.2 B. 2.4~7.2 C. 3~4.8 D. 4~7.2 参考答案:A 答案解析:[解析] 空心板的厚度尺寸视板的跨度而定,一般多为110~240mm,宽度为500~1200mm,跨度为2.4~7.2m,其中较为经济的跨度为2.4~4.2m。
第33题: [单项选择]— What was he doing at this time yesterday — He () to sing a song in English. A. was trying B. is tried C. is trying D. was tried 参考答案:A 答案解析: