挡火闸系指，在通风导管上安装的一种装置，其正常情况下保持____使气流进入导管，而在火灾时____，以阻隔导管流通而抑制火焰通行。
A
暂无解析
A trend that occurs at the same time with the movement to the South and the Weast of the United States is ________.
When _______, water will be turned into steam.
The vehicle was traveling at speeds ________ 90 miles per hour.
At the age of eighty -seven,( )read his poetry at the inauguration of President John in 1961.
William Faulkner once said that( )is a story of “lost innocence, ” which proves itself to be an intensification of the theme of imprisonment in the past.
This is the most beautiful village _______ I visited these years.
Fish is ________ and expensive at this time of the year in this area.
Like all naturalists,( )was restrained from finding a solution to the social problems that appeared in his novels and accordingly almost all his works have tragic endings.
The teacher told us the fact _______.
Police are ________ the disappearance of two children.