Find the mistake:
1- She wants to know whether I will drive her to the airport.
2- It's going to rain heavily. If only I brought my umbrella with me.
3- He must have had difficulty sleeping last night. He said he had anxiety.
4- Do you know how far the sun is from the earth?
5- In the job interview, I was asked If I would mind working at night.
6- If I knew how much it costs, I would tell you.
7- What you think is beyond reach to day can be within reach tomorrow.