If <new-topic> is specified and you are a chanop, or the channel is not in 'private topic' mode (+t), the topic will be changed to <new-topic>.  If <new-topic> is *not* specified, the current topic will be displayed.
如果指定了 <new-topic> 并且您是 chanop，或者频道未处于“私人主题”模式 (+t)，则主题将更改为 <new-topic>。如果 <new-topic> *未* 指定，将显示当前主题。