为什么要加s?The days are long and the nights short.The sun rises early and sets late.我知道第二句第三人称单数人或物名词后的动词要加S,但第一句为什么也要加S?

the days are shout?中的day为什么要加S,以及day前为什么加The The days are long and the nights are short请问在这days和nights为什么要加S the days 为什么要加s 这几个词为什么要加sWhich seasons do you like best?The days are long and th nights are early.seasons,days,nights,为什么要加s the days are long and nights are short. the sun rises early and sets late .两句话里面的s为什么要加s the days are long为什么要加Sthe days are long and the nights are short.还有the sun rises early and sets late 请问这些单词后面为什么要加s?Which seasons do you like best?seasons后面加s是因为季节的复数.The days are long and the nights are short.days和nights后面加s是因为日子和夜晚的复数.The sun rises early and sets late.ri the days 前为什么加the?day为什么加s?如题. The days are longer中,为什么要用“are”越细越好! The summer holiday are comingsoon.holiday为什么要加s in those days（当时）为什么day要加s 为什么要加s?The days are long and the nights short.The sun rises early and sets late.我知道第二句第三人称单数人或物名词后的动词要加S,但第一句为什么也要加S? “How many days are there in a week?”这句话为什么要加“are there”? The will be back in(a few days')time.为什么加s’ The cats are running along the wall.这里的cats为什么要加s? the students are discussing the questions in groups.为什么group 要加S呢 The policemen are in uniform为什么uniform不加s 英语的一些语法问题Which seasons do you like best?I like spring and summer.The days are long and the nights are short.The sun rises early and set late .问下,为什么season day night rise set要加s.详细点.