“低沉地说”可以翻译为 "say in a low/deep voice" 或 "speak in a low/deep tone"。
"say in a low/deep voice" 强调用低沉的嗓音表达，适用于日常对话或描述。
"speak in a low/deep tone" 更侧重语气或音调的低沉，适用于更正式的语境。
例句：He said in a low voice, "I'm not sure about this." （他低沉地说：“我不太确定这件事。”）
She spoke in a deep tone, her voice barely above a whisper. （她用低沉的语气说话，声音几乎低不可闻。）