下列（）材料的抗冻性较差。 ["孔隙率极小的材料","含有大量封闭、球形、间隙小且干燥孔隙的材料","软化系数小的材料","韧性好、变形能力大的材料"]
加强防洪抢险实战演习。各车间每（）必须开展一次防洪演练，并将抢修演练评价表和相关图片报安调科。 ["日","周","月"]
教育目的的价值取向
教育学
In order to acquire a second language， learners will subconsciously use their first language knowledge in learning a second language. This is know as language t（）.
顾客需求有什么特点？
