If he doesn't find a solution to his problem soon, he'll surely flunk out of college.

如果他不能很快找到解决问题的办法，他肯定要被学院退学。

《柯林斯英汉双解大词典》

If he is no good, flunk him.

如果他表现不好，给他不及格。

youdao

About 5 percent of students in the language program flunk out before their freshman year.

参加英语语言课程大约5%的学生会在上大一之前退学。

youdao

Politicians, preachers, lawyers, bureaucrats and, one suspects, journalist-novelists like himself, also flunk his test of masculinity by engaging in namby-pamby occupations.

ECONOMIST: Atlanta burnt again

Asked at the start of the test, if would-be motorists flunk the questions it will count as one driving fault out of the maximum of 15 allowed before a fail.

BBC: L-plate

The Massachusetts Board of Education, for example, fearing most students would flunk, has voted to set low passing scores--just above failing--for a new test students must take to graduate from high school.

FORBES: Fact and Comment