应使用early and earlier

early 是形容词, 比喻说: early one morning
earlier 是比较次。。 比如所：i arrived earlier than you ( 我比你到得早）。

这两个的词的用法跟 good, better 等等的词组 差不多。。

慢慢领悟把！~~

early Friday morning 星期五一早
early Friday afternoon 星期五刚到下午
以此类推

early Friday
earlier Friday 是比较级，只有在比较的时候才用！！

下面的例子引自词典,可供参考:

A lot of drivers will be thinking about the circuit,because we’ve had some rain earlier today. 许多司机将会想到环行路线, 因为今天早些时候下过一点雨。

I rang you earlier but I couldn’t get through. 我早些时候给你打过电话，但是没打通。

a runner who’s beaten Linford Christie earlier thjs year. 今年早些时候打破林福德·克里斯蒂记录的赛跑运动员……

用early 也就是"the early friday "
earlier 只有一种用法 那就是做副词 表示"先前,早些时候" 如:i had seen him ealier in the day
而early 有很多种表示"早,先"的用法 如上面提到的用做形容词修饰friday 还可以后面加一个时间段 做副词 如:"early in the morning" 一大早 等