______ a host of the show is really ___________.

A．Being, a hard work

B．To be, hard work

C．Being, work hard

D．To be, hard-working

宁天城际列车发生信号紧制，在紧制条件消失后会自动缓解，司机正常操作；若紧制条件一直存在，司机凭行调指令以RM模式或者切除车载ATC运行。