1. doesn't do OR does not do
In this case your verb phrase needs to agree with the subject phone. It is singular so the verb phrase must be singular as well. You can either use the contraction doesn't or it can be written out: does not.
2. had
Have needs to be in past tense. The friends are wishing they already (past tense) had the smartphones. They wanted it yesterday, not now, not in the future.
3. best
In this sentence she is saying choosing the one things that is at the top of the list of things about a smartphone. Since there is definitely more than 2 items on the list, best should be used.
4. are used
This needs a helping verb and the correct form of use.
5. children
In this sentence, the author is talking about more than one child. The plural form of child is children.
6. first
An ordinal number is needed her since the author is saying that her Nokia is her first one.
7. me
Me is an object pronoun. In this sentence the subject is it so me is an object.
8. flew
Fly needs to be in past tense since the action happened yesterday.
9. would be
This needs the conditional helping verb would in order to make sense.
