介绍他人的时候经常用this is...
this is Xiaohui.
a,an用于可数名词单数前面，具有不确定意义的事或名词前面
a用再普通名词前面，an用于元音因素前面
the是定冠词，表示特指
选择疑问句标志词是or
Is she a student or an English student?
回答必须是完整的回答
she isn't a student,she is an English student.
What make is it?它是什么牌子的？
It's Volvo.
what特殊疑问词？
where什么地方
who谁
when什么时候
which哪个
why为什么
what color is it?
what is your job.
How many days are there in a year?