Question 1: Most of students did it well, and got full marks.
             Some students don't know how to prove by using induction.

 Question 2: You can use the result of Question 1, but you must explain
it clearly.

 Question 3: You must clearly explain why T2 and {e} contains a cycle, 
 and why not all the edges in this cycle belong to T1, not only copy
professor's hint on your paper.


 You must explain your answers clearly and shortly, don't put many
useless words on your paper. If your answer is perfect, you will get
full marks, and if it is good but not perfect, you get some reduce.