adding ed

[Tdol]

'Do' is wrong there because it doesn't fit the time- if you mean now, use 'are doing'.

[jack]

'Do' is wrong there because it doesn't fit the time- if you mean now, use 'are doing'.

I don't get it, why doesn't it fit the time. what part of the sentence makes it doesn't fit with time?

"It is unlikely that they do something like this since they never used this before."

"It is unlikely that they are doing something like this since they never used this before."

[Tdol]

The second is a possible sentence, but it sounds a bit strained and would require some context to explain it. However, it is an improvement on the first.

[jack]

"I always wanted to get one." <--corect? why? what does it mean? Does it mean he/she wanted one before but now he/she doesnt want one?
"I always want to get one." <--corect? why? what does it mean? Does this mean he/she want to get one and still does?

[Casiopea]

"I always wanted to get one." <--corect? why? what does it mean? Does it mean he/she wanted one before but now he/she doesnt want one?
"I always want to get one." <--corect? why? what does it mean? Does this mean he/she want to get one and still does?

'always wanted' refers to the Past, whereas 'always want' refers to the habitual.

EX: I always want to do my best but sometimes the situation makes that difficult.

EX: In the past, I always wanted to do my best but now I just do what I can and hope for the best.

All the best,

[jack]

"It looks like you never shot a gun in your life." <--correct? why? what does it mean?

"It looks like you never shoot a gun in your life." <--correct? why? what does it mean?

[Tdol]

The first is OK, though I would say 'like you have never fired'.

[jack]

"It looks like you never shoot a gun in your life." <--why is shoot incorrect?

"It looks like you have "killed" him." <--correct?

[Tdol]

"It looks like you never shoot a gun in your life." <--why is shoot incorrect?

It is possible if you mean that you don't think the person is in the habit of shooting a gun, rather than referring to an instance in the past.

"It looks like you have "killed" him." <--correct?

That's fine, though many would recommend using 'as if' instead of 'like' before a verb.

[Casiopea]

"It looks like you never shoot a gun in your life." <--why is shoot incorrect?

"It looks like you have "killed" him." <--correct?

This is a great example of the Present Pefect merging with the Simple Past:

It looks like you (have) never shot a gun in your life.

The speaker has omitted the Present Perfect marker 'have'.

All the best,