Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

If this [?] is not properly [?], any tiny spark can [?] it. If the [?] blows up its top goes flying and can [?] hurt you or a [?]. The installation of [?]-start [?] is recommeded as it [?] reduces the risk of [?] batteries.