问几道关于介词的题目 ,最好说明原因

很高兴回答你的问题.
1.填介词I was doing my home _at__this time yesterday.
this time 在这里指具体的时间,即“昨天的这个时候”,相当于一个时间点,具体的时间点前面是要加at的.this 的时间状语不加at的情况是时间段的时候,即this morning,this afternoon,this Monday,this weekend...这些都不是具体的时间点.
若this time 前面不加at的时候,time 表示次数,意思则变成“这一次”,例子：I don't want to follow your order this time.（这次我不想听你命令了.）
2.请告诉我hear from 、hear of的区别
hear from ：收到...的来信；从...听到（消息,情况等）,强调听到的来源方向；受到...的责骂或警告
hear of ：听说,闻悉；了解
例子：I have never heard from him.我从没收到他的来信.
I have never heard of him.我从来没听说过他这个人.
3.____the age of 13,Fu Mingxia was very famous in China ____the youngest Olympic champion A.At;for B.At;as C.On;for D.In;as
选B.at the age of ...在...岁的时候
be famous as+身份 表示作为什么人而出名,这里the youngest Olympic champion是“最年轻的奥运会冠军”是一种身份,用as
be famous for...是因为什么而出名的意思
4.You know we sell our tea____our samples.A.because B.accord to后面不打了
只有这两个选择的话,选B.because后面应该加完整的句子.accord to有给予、同意的意思.
5.Both Mary and Betty will get married this year .Mary is going to being their honeymoon_____Christmas while Betty____New Year'Day.
A.on ;On B.at;in C.at;on D.by;on
选C.at Christmas在圣诞节； on New Year's Day在新年那天.固定搭配.