Best gift I received Best gift I received

The question is "What is the best gift you have received?" - It is in the present perfect. In this case, it is asking about your "life experiences with respect to presents you have received". To talk about life experiences, we have to use the present perfect. Title: "The Best Gift I've Received".

The best gift I received was my computer when I was a twelve. The best gift I received was my computer when I was twelve.

The best gift I received was my computer when I was a twelve. The best gift I received was my computer when I was twelve.

The best gift I have (ever) received was my computer when I was a twelve. The best gift I have (ever) received was my computer when I was a twelve.

The best gift I have (ever) received was my computer when I was a twelve.

Because of the internet this computer, it allowed me to see the world from another perspective. Because of the internet, it allowed me to see the world from another perspective.

Because of the internet, this computer allowed me to see the world from another perspectives. Because of the internet, this computer allowed me to see the world from other perspectives.

Because of the internet ,this computer allowed me to see the world from another perspective. Because of the internet ,this computer allowed me to see the world from another perspective.

"because of" is a synonym of "due to", "as a result of" etc. "because" provides an explanation as a relative pronoun "I get up early because I like to have spare time in the morning before work". You are correct to say "allowed" (past simple) here because now you are talking about a some event that started (and ended) in the past.

I'm grateful for not having access to a computer with internet before this age, because if I had, probably I wouldn't have played outside anymore and would have lost an important part of my childhood. I'm grateful for not having access to a computer with internet before this age, because if I had, probably I wouldn't have played outside anymore and would have lost an important part of my childhood.

I'm grateful for not having access to a computer with internet before this ageyounger than third, because if I had, probably access, I wouldn't have played outside anymores much and would have lost an important part of my childhood. I'm grateful for not having access to a computer with internet younger than third, because if I had access, I wouldn't have played outside as much and would have lost an important part of my childhood.

I'm grateful for not having had access to a computer with the internet before I received this agegift, because if I had, I probably I wouldn't have played outside anymore and would have lost an important part of my childhood. I'm grateful for not having had access to a computer with the internet before I received this gift, because if I had, I probably wouldn't have played outside anymore and would have lost an important part of my childhood.

You are talking about an event before another in the past (i.e "not having a computer" happened before "I received a computer"), so: Past Perfect. "not having had access". For the same reason, you have to use the 3rd conditional - a unreal past event. This is difficult grammar, and you've made a really excellent attempt.