Translation of surjection in German

From my experience it is better to test it first with other students. It is difficult for me to give you exact information without knowing your teacher's needs. Please send me your email address.
I have your letter sitting on my desk. But, in the last 2 months I have been working on some projects which were very time consuming. I will not be able to start anything new before October or November.
As soon as I went to bed, incredibly loud music starting playing from right beneath my room. The music was so loud that I could not fall asleep despite my jet lag and despite being extremely tired.