采用追踪运行的列车控制方式主要有两种:()、()。
参考答案:调度集中控制;行车指挥自动化
Mr Smith ______ to American 10 years ago and has been there ______.[ ]
A. has gone, since then
B. went, from then
C. has gone, since then
D. came, ever since
以下程序执行后,abc.dat文件中的内容是 #include<stdio.h> main( ) FILE *pf;char *s1="China", *s2="Beijing"; pf=fopen("abc.dat", "wb+"); fwrite(s2,7,1,pf);rewind (pf); /*文件位置指针回到文件开头*/fwrite(s1,5,1,pf);fclose(pf);
A.China
B.Chinang
C.ChinaBeijing
D.BeijingChina