NCE2 lesson58 中 a useful source of income为什么用a 而不用an?看音标的吗？不是单纯看字母的呀？

NCE2 lesson58 中 a useful source of income为什么用a 而不用an?看音标的吗？不是单纯看字母的呀？ NCE2的Lesson41课后习题It looked like a lighthouse.It ______ a lighthouse.It looked like a lighthouse.It ______ a lighthouse.A appeared similarB resembledC matchedD likened为什么A不对? what about us中us为什么用宾格 there is a charity show this weekend,would you like to join us?此句中去掉us不行吗? a flight attendant told us to keep calm .这句话中us后面是不是省略了that excuse us for a give us a told us a Jane tells us a 英语问题,NCE2课本的,急用,明天上课用hold或look的正确形式填空：1,We shall be （ ） a party tomorrow.I am（ ）it very much.2,（ ）!You nearly koncked that jug over!3,They say he is very famous.I shall（ ）him（ ）in Little John gives us a vivid d of this pictureLittle John gives us a vivid () of this picture在括号中填单词 单词开头字母d Each of us has a book.中 each的词性是形容词吗? the man___america will give us a talk___about his country.中填什么介词,为什么? Marry poured us each a glass of own.中哪个是主语,each是什么词性? 在Tomorrow I want to give us a talk .中,为什么要加to. It does us a lot of good 什么意思通常用在什么情境中? Being on a diet is not good for us中“Being on the man___america will give us a talk___about his country.中填什么介词,为什么?