Is there a way to ask expect wait for sometime before running the next send command ?

Hi all,

After expect catches the string I specify, is there a way to ask expect wait for sometime before running the next send command ?
So my script looks like following,

expect "some string"
#How to ask expect to wait for a while
send "next command"

The reason I want to do this is because after the process I deal with sends out the string I expect it may also send out some other strings which depends on the then situation. So I won't be able to ask to expect catch those strings. Or I don't bother to do that because as long as the "some string" is caught by expect I am happy. I don't care the next texts that spawned process outputs. I just need to wait for them to finish then send my next command.

So how to do that ?

Thanks!