很高兴为你解答.
保证正确率~!
正确答案是：
If you don't study hard,you won't be (able) to ( pass) the exam
.如果你不好好学习,你就不能通过考试.
【解析】：be able to do = succeed in doing = manage to do 成功地做成...
祝开心~!
希望能解决您的问题.