无线信号在自由空间的衰落情况是:传播距离每增大一倍,信号强度减小()
A、2dB
B、3dB
C、6dB
D、9dB
参考答案:C
小题1:Which of the following pictures could be Bob?
A B C D
小题2:Alice is worrying about ________.
A. her friends B. her marks C. her height D her weight
小题3:Bob should ________ according to George’s letter.
A.plan his meals
B.talk to his friends
C.join a basketball team
D.learn some French.小题4:George advises Alice to talk to _____ for help.
A.her mother
B.her pen pal
C.her doctor
D.her teacher and friends小题5:Maybe George is probably _________
A. a reporter B an actor C a doctor D an engineer
在第一届全困人民代表大会的开幕词中毛 * * 说:“我们这次会议具有伟大的历史意义。这次会议是标志着我国人民从1949年建国以来的新胜利和新发展的里碑……”材料中的“里程碑”表现在[ ]
A.社会主义制度的建立
B.新的国家领导人的选举
C. * * 党核心地位的确定
D.第一部社会主义宪法的制定