I think 完璧ぐ～のね comes from a phrase ぐうの音(ね）もでない。 This means that, driven into a corner, there's no room for an excuse or objection. A person is beaten up by someone mentally or powerless. ぐうの音 is sound made when you are choked. So, ぐうの音もでない literally means that you can't even make tiny sound from being choked. By the way, please let me give you some corrections on your sentences: 先生は知りませんでしたから、問います→先生が（この意味を）知らなかったので、（ここで）質問（しつもん）します／質問させてください。 手伝いなさい、ね→手伝ってください（ね） I hope this helps you!