人体中含量最多的两种元素是( )
A.氧、钙
B.氧、氢
C.氧、氮
D.氧、碳
人体中各种元素前几位的排序为:氧、碳、氢、氮、钙、磷、钾,含量最多的两种元素是氧、碳.
故选D.
Much to our surprise, his new book became an___ _ success. [ ]
A. instant
B. instructive
C. interesting
D. inexpensive
自动重合闸装置应能在合闸后,加速继电保护的动作。必要时可在重合闸前加速其动作。