Yes, 搞清楚前者为何退出.

You need to find out it is because buyer's reason or house reason for the fall off.

Ask all inspection reports and disclosure package. Normally previouse buyer won't give it to you. But, you at least can get termite report from State Pest Control Board for free or a couple of $. Is it regular sale or short sale / REO?

Put more strick contingency on your offer so you can have more chances to run.

Please check out the neighborhood information. If it is last mintue back out, it must be some hidden reason which it is not easy spot out at the beginning.

Good luck!