1. The next important (A) question we have to decide (B) is (C) when do we have to (D)finish our work.
=> We have to.
2. The food (A) that is cooking (B) in the kitchen is smelling (C) delicious (D)
=> Smells.
3. After he had bought (A) him (B) a new automobile, he sold (C) his (D) bicycle.
=>...