相关单词近義詞 problem 問題, puzzle 難題, riddle 謎, challenge 挑戰, conundrum 謎語, mystery 謎，神秘臨近詞Brainard, brain, brain neoplasms/ radiotherapy, brain ventricle and pool imaging, brain metastases/radiotherapy, brain injuries/rehabilitation, brain self-retaining retractor, Brain Science and Quantum Theory, Brain arteriovenous malformation, brain derived neurotrophy factor, Brain imaging with vascular flow, Brain metastasis/radiotherapy相似詞brainless, brainpower, brainstorm, brainstorming, brainwash, brainwave, brainy, braise, 返回 brainteaser