In addition;
"An interrogative + (で)も" means "any/every", and it expresses complete denial in negative sentences.
e.g.
何でもできます。
I can do anything.
何もできません。
I can't do anything./I can do nothing.
が or は can be used also in negative sentences.
e.g.
田中さんがいません。
Tanaka is not here.
田中さんもいません。
Tanaka is not here, either.