In the Chinese language, both “以前(yǐqián)” and “从前(cóngqián)” can be used to refer to the past, but the meanings of the two words and the ways in which they are used are not exactly the same.
First of all, “从前(cóngqián)” always refers to a time far in the past, meaning “long, long ago” or “once upon a time,” while “以前 (yǐqián)” is closer to the present, meaning “previously,” “…ago,” or “before.”
Cóngqián, yǒu yígè měinǚ jiào Xīshī.
从前， 有 一个 美女 叫 西施。
Once upon a time, there was a beauty named Xishi.
Kathy: Nǐ yǐqián shì zuò shénme de?
Kathy：你 以前 是 做 什么 的？
Kathy: What was your previous job?
Liú Wěi: Wǒ yǐqián shì gè lǎoshī.
刘 伟： 我 以前 是 个 老师。
Liu Wei: I was a teacher previously.
Furthermore, “以前 (yǐqián)” generally refers to a time before now, and it can be placed at the beginning or the middle of a sentence. However, “从前(cóngqián)” is always used at the very beginning of a story.
Yǐqián, wǒ hěn shòu. Wǒ yǐqián hěn shòu.
以前 ，我 很 瘦。 我 以前 很 瘦。
I was very thin before.
Cóngqián, shān shàng yǒu yízuò chéngbǎo.
从前， 山 上 有 一座 城堡。
Once upon a time, there was a castle on a mountain.
Additionally, “以前 (yǐqián)” can be used after time words while “从前(cóngqián)” cannot.
Boss: Mike, qǐng wǔdiǎn yǐqián lái wǒde bàngōngshì.
Boss：Mike， 请 五点 以前 来 我的 办公室。
Boss: Mike, please come to my office before five o’clock.
Zhāng Lì shísuì yǐqián zhù zài nóngcūn.
张 丽 十岁 以前 住 在 农村。
Zhang Lin lived in the countryside before he was ten years old.
In our test, Li Hua wants to know whether Tom can speak Chinese. Tom answers that he has studied Chinese before, which refers to a period of time that is relatively close to the present. Plus, the blank is in the middle of the sentence. This means the correct answer is A.