look up with multiple criteria

[heidiau]

Sheet 1 full list
Sheet 2 list of student taking more than one type of lessons

I want to show the lesson time in sheet 2 column c. The criteria are sheet 2 column a and b. I want the formula can be copied down to the last row. How can I do that?

Some of the students having double sessions for the same instrument will have two individual entries, so remove duplicate cannot suit my needs.

Thank you.