I'm French, I did the exercise but I don't know if it's right Use the comparative forms and at least three of the adjectives below :

easy / difficult / modern / old-fashioned / cheap / expensive / fast / time-saving /slow / varied

I don't understand sentence number 2.

How I read it is: "The choice on the net is less difficult than I'm stones because more varied"

I'm I, right?

On sentence number 4 I would remove the word "is" after the word "and" .

On sentence number 7 I would change the word "is" with the word "are" - because the word "articles" is plural

not sure how to answer your question sorry