施工中混凝土结构产生裂缝的原因是（）。
A.接缝处模板拼缝不严，漏浆
B.模板局部沉降
C.拆模过早
D.养护时间过短
参考答案：B, C, D
根据要求完成句子，每空填一词。
1. He is never here. (改为反义句)
He is _____ here.
2. I like the novel by Smith. (把I改为Tony)
Tony _____ the novel by Smith.
3. She does her homework at school. (改为否定句)
She _____ _____ her homework at school.
脚手架体系中剪刀撑的布置方式是什么？
