搜题请搜索小程序“爱下问搜题”
问题
填空题
火灾危险场所，按其危险程度分为（）、（）、（）。
答案
参考答案：H-1级场所；H-2级场所；H-3级场所
选择题
We couldn't catch up with the others because they ____ too long before us.
A. started
B. were starting
C. have started
D. had started
查看答案
问答题 简答题
物体发生碰撞时产生的应力波有哪些特性？
查看答案
