辞書を使わ___、この記事を読んでみてください。
Q. Which form means 'without using (a dictionary)'?
Translation
Try reading this article without using a dictionary.
Explanation
〜ずに is the written/formal equivalent of 〜ないで 'without doing': 使わずに. なくて states a cause ('because ... not'), and while 使わないで is also correct in speech, the ず-form is the one that attaches as 使わ+ずに here.