I'm an engineer 为什么英语中要用AN而不是用A

今天的英语,i'm working as a project engineer for an oil and gas c 1.I am an engineer,( A ) Are you a teacher or engineer?A,Yes ,I"m a teacher B,I"m an -What do you do?-I'm an engineer.I __ in a company in Wuhan. engineer 前面用A 还是AN 英语小时前为什么加定冠词an而不是a I am gonging to be a teacher.用 an engineer 改为选择疑问 I have_____uncle.He is an engineer.A.a B.an C.the要理由 john is an engineer is a big company用英语解释 半小时用英语讲为什么是half an hour而不是a half hour 为什么字母U用a修饰而不是an 为什么是a unique opportunity 而不是an