she missed failing that class by the skin of her teeth,so I told her she'd better take it again
问题描述：
she missed failing that class by the skin of her teeth,so I told her she'd better take it again
答
by the skin of one's teeth
几乎；仅仅； 差一点就没…；好不容易才…
这句话的意思：她失误差一点儿没通过那门课程,所以我劝她最好还是再来一次.