Sure, I'll help you with that. Here are the sentences with the correct verb forms:

1. I just **have lost** my keys, so I can't open that door.
2. Columbus **arrived** in the New World in 1492.
3. Ninja just **has broken** her leg. She is still in the hospital.
4. Last winter, Hoa **stayed** with her sister in Sapa for three days.
5. **Has** she ever **gone** to Bắc Ninh?

### Explanation and Underlined Clues:
1. **Present Perfect**: "I just **have lost** my keys" (The word "just" indicates a recent action that has relevance to the present moment).
2. **Past Simple**: "Columbus **arrived** in the New World in 1492" (The specific time "in 1492" indicates a completed action in the past).
3. **Present Perfect**: "Ninja just **has broken** her leg" (The word "just" indicates a recent action that has relevance to the present moment).
4. **Past Simple**: "Last winter, Hoa **stayed** with her sister in Sapa for three days" (The phrase "Last winter" indicates a specific time in the past).
5. **Present Perfect**: "**Has** she ever **gone** to Bắc Ninh?" (The word "ever" is often used with the present perfect to ask about experiences up to the present).

I hope this helps!