单项选择题
A.kept in nonmetal containers B.discarded as soon as possible C.cleaned thoroughly for reuse D.kept in the paint locker
A.smoke sensors B.the difference in thermal expansion of two dissimilar metals C.pressure loss due to air being heated D.an electric eye which actuates when smoke interferes with the beam
A.shutting off the air supply B.cooling the fuel to below ignition temperature C.dispersing the fuel D.removing the source of ignition