early and earlier

you have to go to school earlier tomorrow
you have to go to school early tomorrow

哪一个是正确的，为什么？

两个句子都正确，表达的意思稍有不同，
you have to go to school earlier tomorrow 是指你明天必须更早的到学校，earlier是比较级，强调的是与另一时间作比较，比如说你今天7点钟就到了，我要求你明天来的更早一点，比如在7点以前就要到，这里就要用earlier
you have to go to school early tomorrow 这句early是原级，就是指你明天必须早到学校，（不要迟到了），没有与其他时间做比较的意思。

用earlier 形容词 1. 早的;提早的;早产的,早熟的 they were much earlier than i expected. 他们比我期待的早多了。 we had an early dinner today. 今天我们晚餐吃得早。 2. 早期的,早先的,在前的 in his early years, he was a keen basketball player. 他早年热衷于打篮球。 3. 不久的,很快的[z][b] we look forward to an early reply. 我们期望早日得到答复。 副词ad. 1. 早;提早 please come to see me early tomorrow morning. 请明天一早来见我。 please come early. 请早点来。 2. 在开始阶段,在初期 earlier 是early 的比较级 jim always comes earlier than me .指jim比我早

you have to go to school earlier tomorrow 原因:今天可能迟到了,所以要求明天比今天更早些,这里有个比较的意思

第一个意思，早一点儿，表示建议，提议，比平常要更早 第二个意思，大早，只是纯粹时间问题，要早，不要迟到 其实2个都对，只是第一句用得更多。

意思有点儿不同： you have to go to school earlier tomorrow 你明天必须早点儿去学校。 you have to go to school early tomorrow 你明天一大早就的去学校语法来说都对