制作木构件的榫接时，应该注意凿眼与开榫的配合，可采用锯不留线凿留线，合在一起整一线。( )
参考答案：对
They ______ the train to Beijing．Otherwise, they would have returned home．
A．need have caught
B．must have caught
C．must catch
D．may catch
得到必要的资源并获得处理机的进程，其状态是
A．就绪态
B．执行态
C．阻塞态
D．挂起态
