Så

Question 1

Så = derfor

Answer 1

Acts as a konjunksjon
Need a subject or adverb between så and the verb
Acts as a helsetning
Jeg har det travelt, så jeg kommer ikke på festen

Question 2

Så = slik at (so that)

Answer 2

Acts as a subjunksjon
Must have a subject between så and the verb
Han løper så han ikke kommer for sent
Acts as a LEDDSETNING

Question 3

Så = etterpå (afterwards)

Answer 3

Acts as a helstening
Is an adverb so comes just before the verb
Nå skal jeg se på TV, så skal jeg legge meg.