A:two times as much
B:twice as many
C:twice as much
D:as twice as much
在地球的周围只要____ 颗卫星就可实现全球通信.
某同学得了急性阑尾炎,到医院做血液常规化验,化验结果高于正常值的可能是( )
为了校园安全,各学校均安装了监控摄像头,关于监控摄像头成像说法正确的是( )