If you have a mold or mildew problem in your home you will want to use the best chemicals to get rid of it. Mold can destroy the structure of your home and affect your family's health adversely. There are different chemicals you can use depending on where the mold is growing.
Normally the transition from a spoken to an extinct language occurs when a language undergoes language death while being directly replaced by a different one. For example, some Native American languages were replaced by English, French, Portuguese, Spanish, or Dutch as a result of colonization.
This is going to depend very much on the dead language you are thinking of learning. For the major dead (aka extinct) languages, such as Latin, Sanskrit, or ancient Greek, there are still classes taught in the langauges and you will have an opportunity to speak the languages there.