Answer:
1. I think I have lost my car keys. Will you help me look for them?
2. I am looking forward to visiting the Van Gogh Museum in Amsterdam.
3. Look out! There's a bus coming.
4. We can look her phone number up on the Internet.
5. I'm really looking forward to our vacation this summer.
6. I don't know this word. I guess I'll have to look it up.