Instead of buying a dictionary, you can use some free online English- Chinese dictionaries, and among which, below 10 are most powerful and worthy of a try. All of these are much stronger than Chinese-Chinese or English-Chinese dictionaries, providing much more detailed grammatical information and web-based examples. 

1. Nciku.com

Nciku is an online dictionary with English and Chinese for language learners, and you can search Chinese characters, pinyin or English words, the search results will include pronunciation with sound, definitions, and some sample sentences. You can listen to the sample sentences both in Chinese and English.

2. Iciba.com

This is the online service of Kingsoft 金山软件, a software company that has offered electronic dictionary products since the 1990s. One advantage to iciba is the online audio service that demonstrates pronunciation for the entire word or phrase, not breaking it up character-by-character like most online services do.

3. Dict.cn

Dict.cn is a Chinese-English and English-Chinese dictionary wherein user can translate a Chinese word in English and vice-versa. There is also available option of showing the results as images. There is also available option of history as well, for users to see the history of overall word/sentenced, searched by them over dict.cn.

4. Youdao Cidian   

Provides results generated by web search as well as the formal entry from The New Chinese-English Dictionary《新汉英大辞典》.  Generates a larger number of example sentences (in both languages) than the other dictionaries listed here.

5. Chinese- English Dictionary

Provides Chinese- English, English- Chinese translation, as well as calculator services.

6. Bing dictionary

Bing Dictionary is a next generation English-Chinese bilingual dictionary and sample sentence search engine; it is particularly useful as a writing assistant and language learning tool.

7. Chinese Tools Dictionary

Audio Chinese dictionary searchable in Chinese (simplified or traditional), pronunciation (Pinyin or Zhuyin – bopomofo) or English. Chengyu, proper names, examples, synonyms and calligraphy.

8. Zaixian Fanyi

This dictionary does not offer sentences but list huge amount of phrases for you, you will find many terms which may give a hand to your academic articles.

9. Bab.la Dictionary

The Bab.la dictionary is available for multiple language translations. You can search Chinese characters, pinyin or English words, the translation results will show you definitions, similar terms, and sample sentences, all the results are written in both English and Chinese.

10. Xiaoma Cidian

You can search Xiaoma Cidian by Chinese characters, pinyin or English words, the search results will show you pronunciations (without sound), English definitions, radicals, variants, and some frequent compounds.

source：chinawhisper