School starts around 9a.m.and ends about 3.30p.m.为什么这里时间前不用加at?

school starts around 9a.m的around 9a.m做什么成分 At around eight o'clock,l go to school school starts at nine o'clock. School starts around 9a.m.and ends about 3.30p.m.为什么这里时间前不用加at? 高一牛津英语课文语法问题课本上有句话一直很纠结I was very happy with the school hours in Britain because school starts around 9 a.m and ends about 3.30p.m这句话说,我想问为什么school starts around 9 a.m starts 后不加 School starts in S______every year. American's school year starts School starts late in America.为什么starts加s School starts at nine o'clock. Ten minutes later school starts.如何翻译? school starts at nine ten否定句 around the school是什么意思? 英语翻译原文如下：Dear Mona,Do you want to know about my morning?Well,I usually get up at around six fifteen.I do my homework at six thirty,and then I eat breakfast at around seven thirty.At around eight o'clock,I go to school.School starts School starts at eight o'clock改一般疑问句 The school day starts at eight every day The school bay starts at eight every morning是什么意思 School starts at nine o'clock.（改为一般疑问句） School starts at nine o'clock变一般疑问句 school starts at nine o'clock什么意思