you had better find someone else to go with nancy is too sick to go to the concert

you had better find someone else to go with
nancy is too sick to go to the concert

你最好是找别人陪你去 南茜病了不能去演奏会

最好找别人一起
南茜病的太重，没法去演唱会
too +形容词+to+动词，表示太“形容词”了已至于无法完成“动词“
比如
you are too naive to be simple,
你太天真了以至于你无法那么简单

你最好另找一个人陪你去。
Nancy 病得太重不能去看演唱会了。