animals are in danger and there will be        space for them if we don’t take any actions.

A．More and more, more and more

B．Less and less, less and less

C．More and more, less and less

D．Less and less, more and more

根据AQ1029—2007标准要求，低瓦斯和高瓦斯矿井采煤工作面采用串联通风时，被串工作面的进风巷在距进风口（）米处设置甲烷传感器T4。

A、3～5

B、5～10

C、10～15

D、15～20