Language learners' limited lexical knowledge leads to imprecise wording. This is especially true when they attempt to express their emotions. Many learners rely heavily on the traditional thesaurus. Unfortunately, this fails to provide appropriate suggestions for lexical choices. To better aid English-as-a-second-language learners with word choices, we propose RESOLVE, which provides ranked synonyms of emotion words based on contextual information. RESOLVE suggests precise emotion words regarding the events in the relevant context. Patterns are learned to capture emotion events, and various factors are considered in the scoring function for ranking emotion words. We also describe an online writing system developed using RESOLVE and evaluate its effectiveness for learning assistance with a writing task. Experimental results showed that RESOLVE yielded a superior performance on NDCG@5 which significantly outperformed both PMI and SVM approaches, and offered better suggestions than Roget's Thesaurus and PIGAI (an online automated essay scoring system). Moreover, when applying it to the writing task, students' appropriateness with emotion words was 30 percent improved. Less-proficient learners benefited more from RESOLVE than highly-proficient learners. Post-tests also showed that after using RESOLVE, less-proficient learners' ability to use emotion words approached that of highly-proficient learners. RESOLVE thus enables learners to use precise emotion words.