1.You should first look up the words you don't know in a monolingual dictionary given that you cannot translate a word you don't understand.
如果你无法翻译一个生词，你就应首先在单语词典中查找这个生词的各种含义。
2.Using a monolingual dictionary for learners has helped me in another important way.
使用一部为初学者量身定制的单语词典，为我指引了另一条重要的学习之路。
3.Use a monolingual dictionary, but try not to use the dictionary too much.
用英英词典，但不要过度使用。