回复：经验是通过实践总结出来的。

You are right from some points of view. My point is, you need know what is a math questions key points (题筋). It takes sometime to write down the logic behind, but a well trained student can figure out the answer without calculator or algebra in a few seconds. If this is a count down question, I am sure there are kids push the button before we finish question. 

所有跟帖： 

• Yes, that would be a well-trained student. -trivial- ♀ (110 bytes) () 06/12/2012 postreply 07:03:49

• 回复：Yes, that would be a well-trained student. -flagsix- ♀ (323 bytes) () 06/12/2012 postreply 07:24:53

• I fully understand your points. -trivial- ♀ (233 bytes) () 06/12/2012 postreply 07:54:25