TOPIC: Question ? Please

In my opinion, I think the first following sentence is right and the second following sentence is incorrect because the 'consider' must be followed +ing form. But I also can say I consider it necessary to do sth that I found in the dictionary. I was wonder what is difference between "2)" and "3)"??

1)I never consider giving up sth.
2)I never consider to give up sth.
3)I consider it necessary to do sth.

THANKS

you are right in thinking # 1 is right and 32 is incorrect because " consider" must be followed by "+ing" form.
And, you're also right in saying we also use #3. And you ask what the difference is between #2 and #3.
The difference is that #2 does not use the " consider it necessary" construction, which must be followed by the infinitive (to do ) form.
As you no doubt know, there's a long list of other verbs that can be followed directly by infinitives rather than an -ing form, e.g., agree, arrange, ask , hope, learn, etc. The verb "consider" is not in that list, and must instead be follwed by an -ing form. However, the " it is necessary +to do " pattern only takes the infinitive.