謎語!!!!!!!!!!!!!!!!!

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2.Every family needs me
for give you brightness.
With me you can read at night Or do your work in darkness.
b.Which word in the riddle is the opposite of darkness?
3.I am soft and useful.
I help wash the bowls and clean the tables.
I can be wet or dry.
I am a good helper of housewives.
People say Ihelp save the earth
Because they can wash me and use me many times.
b.In the riddle,who like to use 'I'?