目前世界各国卫星电视广播普遍采用的频率为()。
A.S波段
B.C波段和Ku波段
C.ISM波段
D.f1和f2
参考答案:B
下列组织T1值最短的是()
A.水
B.皮质骨
C.肌肉
D.脂肪
E.脑白质
Nancy is considered to be()the other students in her class.
A.less intelligent
B.the most intelligent
C.intelligent as well
D.as intelligent as