What is needed for the space trip is careful preparation.
Whether wild life can be well protected is of great importance.
Who will go makes no differences.
Why dinosaurs died out remains a puzzle.
Which kind of food is the best is still not certain.
It hasn't been decided yet when the new restaurant will open.
It is not clear how gold was found there.
It is hard to understand why there is gravity.
It is a shame that you have to leave so soon.