这是一道英语单选题;——I am afraid I can't pass the exam!

问题描述:

这是一道英语单选题;——I am afraid I can't pass the exam!
----You won't _____ you work hard from now on .
A.when B.if C.unless D.after
欢迎各位积极参与回答,Many thanks!

填unless .意思是;从现在起努力学习否则的话就得挂科