一. 语法选择（每小题1分，共15分）
阅读下面的短文，按照句子结构的语法性和上下文连贯的要求，从1··15 各题所给的A，B， C ，D选项中选出最佳答案。
Each of us fails from time to time. If we are wise, having enough experience and knowledge, we regard these failures as __1__ important part of learning. But often as parents and teachers, we don’t offer this right to our children.
My student Donnie was in __2__. His worry about failure kept him away from classroom games that __3__ children enjoyed. He seldom answered my questions-he was afraid of making mistakes.
