IP地址中，主机地址全为0表示（）。
A．网络中第一台计算机
B．本网络的地址
C．广播地址
D．地址无效
参考答案：B
It is a good time ______.
A．go hiking
B．to go hiking
C．going hiking
D．went hiking
— I phoned you yesterday morning. A girl answered, but I didn’t recognize the voice.
— Oh, it __________ my younger sister. She was in my room at that moment.
A．must have been
B．should have been
C．could have been
D．may have been
