To flock to 常用来形容人们大批的涌进某处，蜂拥而至。
Thousands of people flocked to the shopping centre when the summer sale started.
Youngsters flock to cinemas to watch the latest blockbuster action movies.
Birds of a feather flock together 的意思是 “物以类聚，人以群分”。
Mark's friends are all very wealthy, just like he is. Birds of a feather flock together.