1. Oscillations could render the escalator unclimbable, and it may be a terrorist target. 震动会使电梯不可攀爬，并且它可能会成为恐怖分子的袭击目标。
adj
1. incapable of being surmounted or climbed
Synonym: unsurmountable
2. incapable of being ascended
Synonym: unscalable