The minimum requirement for such a job is a TOEFL diploma.

参考译文：这样的一个工作所需要最低要求是一个托福毕业文凭/证书。

TOEFL diploma=托福毕业文凭

TOEFL=Test of English as a Foreign Language 托福考试

TOEFL托福考试(英文解释： TOEFL is an English language examination which is often taken by foreign students who want to study at universities in English-speaking countries. TOEFL is an abbreviation of (缩略＝) 'Test of English as a Foreign Language'.）

I've been out of circulation in order to prepare for the TOEFL.  

为了准备托福考试,我已经不从事社交活动.

His English was good enough for him to pass the TOEFL.  

他的英语够好的了,可以通过托福考试.

He coaches people for TOEFL examinations.  

他指导人准备托福考试.

Do you think the TOEFL score is a good yardstick for English proficiency?

你认为托福成绩是一种衡量英语流利程度的好标准 吗 ?

(2)diploma  n(大学)毕业文凭，学位证书;(美国中学的)毕业文凭 (英文解释：A diploma is a qualification which may be awarded to a student by a university or college, or by a high school in the United States.）

The course leads to a diploma in psychiatric nursing.  

读完这门课程可以获得精神病护理文凭.

She won her diploma in only three years.  

她仅用三年时间就取得了毕业文凭.

She worked hard to earn her music diploma.  

她刻苦用功,以求获得音乐学位证书.

The university may revoke my diploma.  

大学可能吊销我的毕业证书.