There is a "f"in the word "sofa".哪里错了?

问题描述:

There is a "f"in the word "sofa".哪里错了?
从There is a in theword中找!

上面两句正确应该是There is an "f" in the word "sofa".
There is an in the word.
用a 还是an 看的是下一个音词是不是元音音标开头,而不是以元音字母为标准.