do zookeeper allow dynamically add server?

I note that user need edit zoo.cfg to tell zookeeper the number of the servers before I start the zookeeper server.

server.1=x.x.x.x:2888:3888
server.2=x.x.x.x:2888:3888
server.3=x.x.x.x:2888:3888

Could I add the zookeeper server to the system when the system is running?

BRs
Gaofeng