31.  The main reason of this is the work of the teachers is too hard and can't get so much.

32.  This is the main reason why euthanasia causes so much controversy in the world.

33.  Even in more advanced socialism coutries though goverment apply this principle to the whole society, there are some unfair phenomina existed Of course there are many reasons to this kind of unfair thing but the main reason is that .

34.  Television can use to explain part of the main reason that the juvenile delingueney is so universal today and has the tendency of increasing.

35.  The danger and threat to humanity itself certainly is the main reason --- everyone understand that and it needs no more discussion.