甲烷是无色、微有葱味的气体，难溶于水。当空气中甲烷浓度高达多_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题单项选择题

甲烷是无色、微有葱味的气体，难溶于水。当空气中甲烷浓度高达多少时才有毒性？（）

A.25-30%

B.80%

C.90%

D.10%

答案

参考答案：A

选择题

Reading is an experience quite different from watching TV; there are pictures _____ in your mind

instead of before your eyes. [ ]

A. to form

B. form

C. forming

D. having formed

单项选择题

为上呼吸道感染发热患儿物理降温时，体温应降至（）

A.37℃

B.37.5℃

C.38℃

D.38.5℃

E.38℃以下