SDH的中文解释是：（）
A、准同步数字系列
B、同步数字系列
C、准同步模拟系列
D、同步模拟系列
参考答案：B
the key to the car when my boss came towards me.Finally I could drive him
home as usual.
A．Never had I found
B．Seldom did I find
C．Hardly had I found
D．No sooner did I find
我国市政工程建设施工企业（承包商）的资质等级可分（）级。
A.三
B.四
C.五
D.六
