Chinese joke translation

导师出了一道考题：牙疼、萝卜烂地里、女友怀孕有什么共同点？考生A答：都是虫子惹的祸。 导师曰：尔可读研！ 考生B答：拔晚了。 导师曰：汝可读博。请记住报名序号，再次登录时必须填写报名序号！ As instructor expresses a question:tell me the common thing between toothache,carrots rotten on the ground, girlfriend got pregnant.The first student answers: all are done by little things.Instructor:You,qualified for master degree studies. The second student says:A bit late to get the stuff out. Instructor nods:You, qualified for doctor degree studies.