是这样，sundays表示习惯性、经常性的动作
它是一般现在时的时间状语
而on sunday则不是，可跟一般过去时或一般将来时

为什么They like to go out for a trip on sundays,的Sundays要加s？

on sundays表示每个周日，on sunday表示某个周日。

加不加s因句意而定。

we often play football in park on --------- 填sunday 还是sundays

Sunday
我们通常星期天在公园里踢足球。

sundays什么意思

sundays意思是星期日。

Sundays：adv.于每星期日；n.星期日（Sunday的名词复数）；星期天；每逢星期日出版的报纸；星期日报。

句子

1、What happens on Sundays?

2、douBle time for Sundays.

3、Sundays fly by like lightning.

4、We play volleyball on Sundays.

5、SHEX Sundays and holidays excepted.

6、We're mostly out on Sundays.

7、except(for)Sundays and holidays.

8、Algiers Sundays are among the most sinister.

9、I usually go shopping on Sundays.

10、Is the museum open on Sundays?

11、The shop is open on summer Sundays.

12、We are mostly out on Sundays.

13、The museum is closed(to visitors)on Sundays.

14、I used to go to an English salon on Sundays.

15、On Sundays,what time do you have lunch?