Choose the word from the drop-down menu that completes each sentence.

a/an__star system is made of two stars.

a/an__star system is made of no more than a few thousand stars.

a/an__star system is made of more than a million stars.

The chemical reactions lab we did is typically called a "copper plating lab,  because the acid solution cleaned the pennies and made the copper look shinier;   the acid solution cleaned the paperclips and made them look like pennies;   &   the copper from the pennies was removed, and then added to the paperclips.