手机的无线通信可以由同步通信卫星来实现。
参考答案:错
属于伤寒杆菌抗原的是()
A."甲"鞭毛抗原
B."乙"鞭毛抗原
C."H"抗原
D."丙"鞭毛抗原
E."O"抗原
Our teacher demanded that all of us ______ English every day.
A.should practise to speak
B.would practise speaking
C.could practise speaking
D.practise speaking