Here are the incorrect parts in each sentence along with their corrections:

1. **A**: "Never before" should be corrected to **"I have"**.
- **Correction**: "I have never before visited such a fascinating place."

2. **C**: "impact of the increasing" should be corrected to **"impact of increasing"**.
- **Correction**: "Many optimistic people have made predictions about the positive impact of increasing mechanization on human life."

3. **B**: "helped her overcoming" should be corrected to **"helped her overcome"**.
- **Correction**: "It was her strong determination that helped her overcome the physical and emotional pain that followed her accident."

4. **C**: "there will be no space leaving" should be corrected to **"there will be no space for leaving"**.
- **Correction**: "Many people are afraid that in the future there will be no space for leaving human beings..."

5. **C**: "at great reduced prices" should be corrected to **"at greatly reduced prices"**.
- **Correction**: "Dresses, skirts, shoes, and children’s clothing are advertised at greatly reduced prices this weekend."

Here’s a summary of the mistakes and corrections:

| MISTAKE | CORRECTION |
|----------|------------|
| 1. A | I have |
| 2. C | impact of increasing |
| 3. B | helped her overcome |
| 4. C | there will be no space for leaving |
| 5. C | at greatly reduced prices |