“Whether (or not)” is high frequency you need to learn in Korean. The grammar rule is v.s. + (ㄴ/은)지 for present. For instance, I don’t know whether you like it/ 나는 네가 그것을 좋아하는지 모르겠다: 좋아하다 is action verb, so need to add 는지 =좋아하는지. Remember when there is 하다 at the end of verb stem is action verb. Let see one more example with descriptive verb “덥다/hot (weather)” – I don’t know tomorrow will be hot/ 내일 더울지 모르겠어요. 덥다-더우-더울지. As you see, I added ㄹ instead of ㄴfor future tense. If it is present tense, you should say 더운지, and with past tense you should say 더웠는지. The grammar for past tense is “+ㅆ는지”. For the 좋아하다 is 좋아했는지. Please read examples below with all tense.

먹다/to eat

I don’t know whether you ate/ 네가 먹었는지 모르겠다.    Past

I don’t know whether you eat/ 네가 먹는지 모르겠다.        Present

I don’t know whether you will eat/ 네가 먹을지 모르겠다. Future