MSC只采用24位信令点编码。（）
参考答案：错
The young boy has come to himself in hospital now. But he ___ unconscious for three days.
A．has been
B．was
C．had been
D．is
道路的防护林带一般应距离路基( )。
A．1～5mB．5～10mC．10～30mD．50～100m
