You can buy _medicine___ in the shop before eight o'clock in the _evening___ because the shop opens late第一个空：1、it2、they3、their 3、them理论上it跟them都可以，得根据上下文。这个句子前面应该还有内容吧，光从这个句子看不出应该是用单数it 还是复数them