单项选择题 The ZXMP M900 is applicable to ultra long-haul transmission and the system reach can be up to （） at the maximum 。

单项选择题 In a ZXMP M800 system using 100M monitoring, the order-wire and protection switching commands are delivered to related network elements of multicast groups. Each system has a maximum of （） multicast groups.

填空题 ZXWM M900密集波分复用光传输系统中采用的超长距放大技术包括大功率（）技术和（）放大器技术