简述GSM的帧结构
参考答案:
每一帧含8个时隙,时间4.62ms,包含数据156.25bit,51个26复帧或者26个51复帧组成一个超帧,2048个超帧构成一个超高帧。
苯丙酮尿症患者应限制下列哪种食物成分()。
A.脂肪
B.维生素
C.半胱氨酸
D.苯丙氨酸
E.碳水化合物
With respect to closed-end investment companies, generally they:()
A. buy shares back from investors who want to sell.
B. have the market price of their shares determined by supply and demand.
C. sell additional shares only through the secondary market.