4月15号的OVA里的一个句子“Experts at the national institutes of health say to lose weight a person should do an hour of moderate to intensive physical activity most days of the week. ”,对于 an hour of moderate to intensive physical activity ,这里的to是什么成分?似乎有点语法上的错误。我自己听写的到和后来答案对时是一样的,大家觉得应该怎么解释这个to呢?