For beginners, and elementary and lower-intermediate learners, a( )dictionary is essential as they do not know enough of the target language to understand fully a monolingual dictionary.
【正确答案】：BILINGUAL
【题目解析】：本题考查词典的选择。对于初学者和中低级学习者而言，一本双语词典是必不可少的，因为他们对所学的语言还不够了解，不能完全读懂一本单语词典。
