Yes, you absolutely can. If it weren't for the story I'm about to tell you, I'd say it's hopeless.
In year 10, I had a hopeless teacher that taught us nothing. She left at the end and we got a MUCH better teacher. In December Year 11, I was still averaging a grade 4, getting around 28% in my tests. But I got a much better work ethic with this new teacher of mine, and she was really hard working too. I worked my butt off for 3-4 months and bumped myself up by about two grades in my school's March mock exams, where I got 50%, which was about a grade 6. Now I'm hoping I had the same performance in my real exams that just went, and I got a grade 6 or above.
Like someone said up there, you have to practice and ask help for questions on each practice paper that you don't understand.