单护盾掘进机适用于（）。
A.软岩
B.硬岩
C.极硬岩
D.破碎岩层
参考答案：A
Due to the widespread ______ of this medical technology, more diseases can be discovered and treated at an early stage.
A．presentation
B．appreciation
C．qualification
D．application
消化性溃疡最易发生大出血的是
A．幽门管溃疡B．胃小弯溃疡C．十二指肠球部溃疡D．球后溃疡
