Условие задания:

3 Б.
Read these sentences and complete them with should or should have + the verb in brackets.
Write your answers, don't use capital letters.
1. I’m in a difficult position. What do you think I _____? (do)
2. I’m sorry that I didn’t take your advice. I _________ what you said. (do)
3. I posted the letter three days ago, so it _________ by now. (arrive)

Raymond Murphy. English grammar in use- Cambridge: CUP, 379p.