单项选择题
A device fitted over the discharge opening on a relief valve consisting of one or two woven wire fabrics is called a（）.
A.flame stopper B.flame screen C.flame filter D.flame restrictor
单项选择题 A device used to enlarge the size of an existing bore hole, having teeth arranged on its outside circumference to cut the formation as it rotates is a (n)（）.
单项选择题 A Doppler log in the bottom return mode indicates the（）.
单项选择题 A Doppler log in the volume reverberation mode indicates（）.
