题干
— All the salt is sold out!
— People are crazy! experts say there is no use eating salt to prevent radiation(辐射), some people still don't believe it.
A：Unless
B：Although
C：As a result
D：In order that
答案(点此获取答案解析）
B
2B（g）+ C（g），若反应物浓度由0.1mol·L－1降到0.06mol·L－1需20s，那么由0.06 mol·L－1降到0.024 mol·L－1，需要反应的时间是（ ）