reduce sb. to doing sth.
使某人沦为做某事。
这里的to是介词。
请研习经典例句：
The Americans reduce the people from all over the world to working for them by successful financial and trade wars.
通过成功的金融和贸易战，美国人使全世界的人都为他们工作。
reduce sb/sth (from sth) to sth/to doing sth
使陷入（更坏的）境地；使沦落；使陷入窘境
All the buildings in the town have been reduced to rubble.
城里所有的建筑都成了废墟。
Entire suburbs have been reduced to rubble.
整个市郊都变成了一片废墟。
The Normans built the castle which was reduced to ruins under Cromwell.
诺曼人建造了这座后来在克伦威尔统治时期变成废墟的城堡。
She was reduced to tears by their criticisms.
他们的批评使她流下了眼泪。
The attentions of the media reduced her to tears.
媒体的关注把她弄哭了。
They were reduced to begging in the streets.
他们沦落到沿街乞讨。
He was reduced to begging for a living.
他不得不以乞讨为生。
She is reduced to stealing to feed her hungry family.
她沦落到要靠偷窃来养活饥饿的家人。
They were reduced to extreme poverty.
他们陷入极端贫困的状态。
It was embarrassing and sad to see this man reduced to a mumbling wreck.
看见这个人变得口齿不清、弱不禁风，真是让人既难堪又悲哀。
The people here are reduced to dire poverty because of ( the) natural disasters.
这里的人们由于自然灾害而穷不聊生。
The enemy were thus reduced to a passive position in which they found it hard to give up the battle and yet had to give it up.
敌人于是就陷入了欲罢不能，而又不得不罢的被动地位。
This girl was reduced to becoming a prostitute to earn a living.
此女子为了生活沦为妓女。
The elections have been reduced to a farce.
竞选演变为一场闹剧。