第17题: [单项选择]The little boy had no choice but to look on ______ as his mother was seriously injured in the traffic accident. A. help B. helpless C. helpness D. helplessly 参考答案:D 答案解析:本题考查词形的转换。考查的词根help是名词或动词,意为“帮助”;加后缀-less变否定形容词,意为“无助的”;再加-ly后缀变副词,意为“无助地”;没有加-ness变名词的形式。该句意为:当他的母亲