科学探究方法与说明文写作 — 英语词汇题

根据句意及首字母提示补全单词，并写出其中文释义：1. After months of experiments, the scientist finally published his research findings in a famous j______（期刊）. 2. It took great courage to c______（挑战）the widely accepted theory of his time. 3. Careful o______（观察）of natural phenomena is the first step of scientific inquiry.