【题目】—Should I look up the new words each time I come across some?
—No, refer to your dictionary only ______.
A. where possible B. when necessary C. if ever D. if so
在线课程【答案】B
【解析】
试题分析：句意：—每次遇到生词都应该查字典吗？—不是，只在必要的时候查。选项为省略句，完整形式是when it is necessary.只有B项符合题意，故选B.