河道等级划分的主要依据有哪些？等级认定权限如何规定？
人耳感觉哪个声音响些，可以比较声音的哪个度是（）。 ["声级","响度","响度级","声压级"]
一般情况下闸孔出流的能量损失主要是局部水头损失。（）
You have a computer that runs Windows Vista. You run ipconfig /release from the command prompt and receive the following error message: “The requested operation requires elevation.” You need to release the IP address for the computer. What should you do?（） ["A","B","C","D"]
舌接型
浅孔爆破和深孔爆破如何区分，各适用于什么场合？
