The drilling circles generally considers that for the drill stem in crookedhole, the phenomenon of losing stability will not happen, but a detail theoretical proof is not seen.
钻井界普遍认为，在弯曲的井眼中钻柱不会发生失稳现象，但未见到详细的理论论证。
2
At the mention of the old black rabbit hole, the small gray doves arrive immediately to the spirit, he head a little crooked, others had nothing on deaf ears.