1. Mistakes don’t just happen; they occur for a reason. Find out the reason，and then making the mistake becomes ___ .
A. favorable B. precious
C. essential D. worthwhile
【解析】选D。本题考查形容词作表语。句意为：错误并非无缘无故发生；它们的发生是有原因的。找出原因，那么犯错误是值得的。favorable 有利的，赞成的；precious 珍贵的；essential必要的，基本的；worthwhile 值得的；由句意可知D项正确。
