My favourite teacher is leaving? What do I do?

My science teacher is leaving. He's not our actual teacher he's like a sub but he tought us almost for the whole semester now. The actual story is. My actual science teacher was on a leave. He tought us for only one week then he had to go for a surgery. He cannot even teach(not to be rude). He mumbles and he makes everything so hard. We started doing significant digits for the first week and he made it so hard but when the sub tought us that seemed so easy to us. Our sub was suppose to teach us for the rest of the semester that means till January but our sub got an e-mail yesterday from our actual teacher that he might come at the start of December that mean next month. And if our actual teacher comes then our sub won't be in te school anymore ;(. We are not sure if he will come on December or not. He said he might.....

I don't want my sub teacher to go. He's so nice and caring. He teaches us soo well. He's my favourite teacher and I'll miss him a lot. I hope he never goes and I wish I could have him for the whole semester and for the rest of my school years :) I feel soo depressed and sooo sad. I actually feel like crying. When he was giving this news today I couldn't stop crying. I hide my face under the desk and I was crying. He loves our class and no one wants him to go in our other class and in the other classes. We don't want our actual teacher to come.............

What do I do? Should I give him a card/present before he leaves?

Please leave some feedback!