原文The Thing's second ability will check as your beginning of combat step starts to see if you've cast a noncreature spell this turn. If not, the ability won't trigger at all. You won't be able to cast a noncreature spell during your beginning of combat step in time to have the ability trigger.
原文You don't choose targets for The Thing's last ability at the time it triggers. Rather, a second "reflexive" ability triggers when you pay this way. You choose targets for that ability as it goes on the stack. Each player may respond to this triggered ability as normal.