B.只有H20T支持夜景模式,H20不支持
C.只有H20T支持智能跟踪,H20不支持
D.H20没有热成像模块
B.只有H20T支持夜景模式,H20不支持
C.只有H20T支持智能跟踪,H20不支持
D.H20没有热成像模块
B.按压监控【↑】键2S以上,将光标移到“转入20km/h限速模式”选项,按压【确认】键
C.将光标移到确定选项处,再次按压【确认】键
D.缓解列车直接开车
E.2分钟后,监控装置开口限速45km/h,司机以不超过45km/h运行至前方出站信号机前
A、πS#,C#(SC)÷πC#(σTNAME='LIU'(SC)) SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND NOT EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
B、πS#,C#(SC)÷πC#(σTNAME='LIU'(C)) SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND NOT EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
C、πS#,C#(SC)÷πC#(σTNAME='LIU'(C)) SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
D、πS#,C#(SC)÷πC#(σTNAME='LIU'(C)) SELECT DISTINCT S# FROM SC WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
A、可以减少CPU的引脚数目
B、I/O端口不会减少用户的存储器地址空间
C、I/O指令的执行速度更快
D、I/O指令的地址译码更方便
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