Cohesion
So, neither,
  nor
You can use short sentences that start with so
  or neither or nor
  to say that you agree or coincide with what another person says. 
The structure of these sentences is so, neither
  or nor + auxiliary
  verb + subject.
The auxiliary verb is repeated from the first speaker's sentence, or if there
  is no auxiliary verb, you use the auxiliary do
  or did. 
 -  A: I'm
	from Toronto.  
 
  - B: So am I. (= You are from Toronto,
    and I am from Toronto too.) 
 
 - A: Jim
	can swim.
 
  - B: So can I. (= Jim can swim, and I
    can swim too.)
 
 - A: Sharon
	likes jazz.
 
  -  B: So does James. (= Sharon likes jazz,
    and James likes jazz too.)
 
 - A: Bill
	went to Paris last month.
 
  -  B: So did Mary. (= Bill went to Paris,
    and Mary went to Paris too.)
 
If you agree or coincide with a positive sentence, you use so
  + auxiliary verb + subject.
 - A:
	I think Elvis is dead.
 
 - 
	B: So do I.
 
If you agree or coincide with a negative sentence, you use neither
  or nor + auxiliary verb
  + subject.
 -  A:
	I can't understand this.
 
  -  B: Neither can I. (Nor can I.)
 
 - A: I don't
	like Walter.
 
  - B:  Neither do I. (Nor do I.)
 
 - A: I'm
	not hungry.
 
  -  B: Neither am I. (Nor am I.)