当设计对混凝土的弹性模量有要求时，在现场施工时，标准养护试件28天弹性模量试件不得少于（）。
A.1组
B.2组
C.3组
参考答案：A
用适当的介词填空。
1. It’s my grandmother who cooks ________ us every day.
2. Her parents want her to marry the young man who is _______ a good family.
3. Who helps you _______ your homework in the evening?
4. My grandfather used to go to work ________ his bike.
5. They weren’t very rich, but they were happy _______ those days.
公关概念的产生是组织（）的演化的结果。
