How does exaggeration create meaning in this cartoon?
the small flamingo and fish show the insignificance of
wildlife.
many of the animals in the cartoon are covered in oil,
showing the extent of the oil spill.
the water is bright, showing that our effect on the
environment is not as bad as seems.
the enormous footprint shows the extensive damage of
the oil spill to the environment.

type of error:

the error in the sentence is a "dangling modifier". a dangling modifier is a phrase, word or clause that "dangles" because there is not target to modify. in this case, "after mopping the floor" is the dangling modifier since it has no word to modify. the noun "house" cannot mop the floor; therefore there is a mistake in the writing of the sentence.

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.

a) madame podtochina used witchcraft to make it disappear.