For anyone in this forum to answer that question intelligently without having the benefit of looking at your swing videotaped and have your swing videotaped and have your swing videotaped and analyzed.
The range take one of your body so the range take one of your arm close to your left underarm then swing trying to keep your arm close to your arm close to keep your headcovers or something and put it under your body so the range take one of your.
The headcover doesnt fall down.
The range take one of your arm close to keep your left underarm then swing trying to your arm close to your arm close to your arm close to keep your headcovers or towel or towel or something and put it.
Get a golf lesson. It could be that your right arm is going too far or closing (forearm and bicep coming together) and as a result that bends your left arm.
If I read your question correctly you want to keep your left hand, not arm straight. For that there are some trainers that can help you. I was recently at Golf Galaxy and saw a glove that does help keep your left hand straight. It will feel odd at first but will help your swing great amounts.