1)guard,v./n.保卫，守卫，提防 n.哨兵，警卫，看守2)defensive,防御的，保卫的n.防御,守势3)The sentries alternate their watch.,哨兵们轮流看守。4)"purely defensive defense",专守防卫5)To guard with a picket.,以哨兵防卫6)defend,v.防守,保卫;为…辩护,为…答辩
用法例句
According to "Peaceful Constitution", especially article 9, Japan set its military strategy which is called "purely defensive defense".