keystones

例句:

• The Work Deletion and Keystones of Short Message Chicane Casesin Our Country.
  我国应对短信诈骗案件的工作缺失及重点.
  
• The visibility of tracks in these tiny keystones is superb ( see picture below ).
  这些小楔石中的轨迹其可视性非常的好.
  
• Perfect our speech is one of the keystones of an authentic spiritual program.
  改善我们说话的能力是一项实实在在的基本心灵课程.
  
• In Yellowstone, where wolves are keystones, coyotes take the mesopredator role.
  来自SA