As with?

Posted by Sphinx on July 12, 2003

_ with hurricanes and tornadoes, thunderstorms are formed when a warm air mass meets with a cold air mass. (the answer is "as")

I saw this sentence in an English cloze test. I'm confused by "As with" here, what does it mean? I've never seen as and with can be put together to form a phrase! Other examples?

• As with? ESC 07/12/03
  • As with? GPP 07/26/03