mayday吗?还是MAY DAY?还是May day?还是May Day?

mayday吗?还是MAY DAY?还是May day?还是May Day? 是说 on May Day 还是说 at May Day in May day?还是on May day?五一节可是7天. 是说 on May Day 还是说 at May Day啊 mayday is the [填一个单词] day of a week 请问英文 Mayday 和求救有关吗? The second Sunday in May is Mothers' Day 另一说法：The second Sunday of May is Mothers' Day .这两种都对吗?还是有什么区别? 英语中,节假日前是用什么介词呢?比如说在五一那一天,是in the May Day,还是on the May Day? 这句话（英语）有错吗?it happened in the year of may 18th,2010.不知道这句话有没有错.还是应该这样写,it happened in the day of may 18th,2010. The book may be useful to me some day so I 留着 it in my study.用keep还是kept HE MAY BE IN THE ROOM还是HE MAY IN THE ROOM?BE必须有吗? the whole day=all the day 还是all day,whole只能加可数名词吗 是Labor's Day 还是 Labors' Day? in the day还是on the day? in rainy day还是on rainy day on open day还是in open day? teacher's day还是teachers' day 是a Sports Day还是Sports Day?