keystone造句
61. The fourth and fifth chapters are the keystone of this article.
62. The AMT remote management function subsystem and the communication subsystem are the keystone of this system.
63. To ensure the stable operation of resource dry- up mine enterprises' closedown and bankruptcy process has become the premise and keystone of the whole work.
64. UGI Utilities, which serves Trimble and homes across the Keystone State, saw a record of more than 5, 500 customers converting to gas in the year that ended in September.
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