1.am/watching
2.to have
3.is built
4.came/was cooking
5.haven't visited

IV
1.The post office is not as high as the hospital.
2.Their old house was sold last Sunday.
3.The girl you saw at the party last night is my sister.
4.The policeman asked the little boy what his name was.

V.
1.It is officially known as Tet Nguyen Dan, or Tet
2.It begins between January twenty-first and February nineteen.
3.They tidy their houses, cook special food, clean anf make offerings on the family altars
4.Because Vietnamese people believe that how people act during those days will influence the whole year