宾语从句和间接引语中的anybody和somebody怎么变

宾语从句和间接引语中的anybody和somebody怎么变
请问这个句子如何用括号里的话改写成宾语从句?
Is there anybody in the room?(He wants to know...)
还有这个,请问怎么将下面这句话改写成间接引语?
"Is anybody waiting to see me?" asked the manager.
改写后用somebody呢还是用anybody?为什么?
教学参考书上的答案分别是：
He wants to know if there is somebody in the room.
The manager asked if anybody was waiting to see him.
请问究竟是为什么呢？