* * 中段1/3是由下列哪项发育而来
A．苗勒管中段
B．午非管头段
C．午非管中段
D．泌尿生殖窦
E．苗勒管头段
参考答案：D
It has been announces that all takers ____ remain in their seats until all the exam papers have been collected.
A．can
B．may
C．shall
D．will
改善维修是为了消除设备的先（）或频发故障而进行的维修方式。
