英语句子分析如下【这个boy右手在车祸中短了,没有left arm】the only known defense for

英语句子分析如下
【这个boy右手在车祸中短了,没有left arm】
the only known defense for that move is for your opponent to grab your left arm.
the boy's biggest weakness had become his biggest strength.
请分析第一句话【the only known defense for that move is for your opponent to grab your left arm】的主语 谓语 宾语 和其他成分,如 补语是哪一句