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)（）.
A.enlarge bit B.casing bit C.hole opener D.casing opener
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（）.
单项选择题 A Doppler speed log indicates speed over ground（）.
