其实as有两种意思
一个是,因为,而另一个是,当
就是说,as可是当作because,也能当成是when
father step in as i'm doing homework
father step in when i'm doing homework
当我在做功课时,爸爸进来了.
i cannot go home as it's raining now
i cannot go home because it's raining now
我不能回家,因为现在正在下雨.
所以,as和because两者都能换着来用.
要是说该用哪个,就要看你自己的语感了.