Would you please be more specific? What exams are you taking? Do you mean you are taking exams in three weeks? What notes aren't done? If I know more, I can provide more help.
Here's a study tip though--flash cards. You can make flash cards. You can use different colors for different subjects. Just by writing down the question and answer helps retention immensely.
There's also a trick to using the flash cards. As you read them, if you get the answer right, move it to the back of the deck. If you get it wrong, put the card somewhere in the middle. When you do it that way, you are reviewing the material you don't know the most. It really works.
Why don't you create flash cards for the notes that are undone?
Another way to study is divide your paper in half. Write the key concept on the left and all the ideas associated with it on the right. Be sure to summarize. Research shows reading those notes seven times improves your grade. The very practice of creating notes and flashcards counts as studying.
Also try to calm down. Study and keep reminding yourself you can do this.
thanks for the suggestions..actually it's my terminal exam and we have a lot of pressure in the college. we have college time from morning nine to five in the evening. the teachers check the notes daily and it's difficult, either to make notes or to study for the exams..also we have eight subjects a day along with practicals..