1. The correct answer is D. "have" should be replaced with "to have had" to maintain proper verb tense agreement: "I look forward to having had the resolution to the problem I have mentioned."

2. The correct answer is B. "while" should be replaced with "when" to indicate a specific point in time: "They have moved nothing in your room when they sent you to the hospital."

3. The correct answer is A. "didn't" should be replaced with "don't" to maintain proper verb tense agreement: "Aren't you afraid that they will sack you if you don't start coming to work on time?"

4. The correct answer is B. "who's" should be replaced with "whose" to show possession: "I had to drive to the factory to pick up my brother, whose car wouldn't start."

5. The correct answer is D. "getting" should be replaced with "to get" to maintain proper verb form: "It was not easy for us to get tickets for the concert."