1.What do you usually do on Sunday?

问题描述:

1.What do you usually do on Sunday?
不加s对吗?
2.What do you usually do on Sundays?
为什么+s?

1.What do you usually do on Sunday?
要加s或在Sunday前面加【不定冠词a表“类别”】.
2.What do you usually do on Sundays?
因为【可数名词+s】表【类别】,指【星期天】这个类别.