Pressed from his parents, and ________ that he has wasted too much time, the boy is determined to

stop playing video games. [ ]

A. realizing  

B. realized

C. to realize 

D. being realized

关于体内钙的叙述，下列哪项不正确

A．血清钙的浓度一般相当稳定
B．血清钙浓度为2.25～2.75mmol/L
C．不少外科病人可发生不同程度的钙代谢紊乱
D．机体内的钙99%以磷酸钙和碳酸钙的形式贮存于骨骼中
E．血清中的非离子化钙不到半数，但却起着维持神经肌肉稳定性的作用