Read the given query and classify it as a 'Good' or 'Bad' query depending on how well the query is formed, 'Bad' being the expected output for a not so well formed query and 'Good' being the expected output for a well formed query. A query may be wrong based on common sense or general facts, but if it is well formed, you should answer with Good.

How does a virus infect a host ?
Good

Where can you by a BB gun ?
Good

But how did david and selena ?

Bad