You are walking down the street and someone
you don't know smiles at you.

Quelqu'un dans la rue (que vous ne connaissez
pas) vous sourit.

I'd smile back (if the person is female, anyway).

I usually smile back.

I smile back and continue walking.

I wish there were more people like this.

I would smile back and keep walking.

That was nice of him/her.

A smile lighten up anyone's day.

I feel really good about that, and smile back.

I'd think,do I know this person

I smile back.

I would smile and/or wave back

it cheers me up when random people are nice.

I smile back out of courtesy.

it makes me happy when random people are nice.

I smile back if that person seems nice

I would believe that the person is very friendly.

A thought flashes through my mind, "there are still friendly
people around"

same sex: stupid freak; opposite: hmmm...

smile back :)

I'd smile back and ask how they were doing.

I would probably ignore them

I smile back.

I would smile back and say hi.

I smile back and probably say "hi".

I am usually suspicious of seemingly overly polite people.
I don't respond

The person is happy about life.

I smile back if they seem friendly.

smile back, walk on

moi aussi

je lui réponds en souriant

Je lui souris

je lui rends son sourir.

Je sourirais en échange.

si elle est jolie, je souris aussi...

je souris ou je dis bonjour

je les ignorerais

Je lui sourirais.

je fais de même

je lui souris

je souris

je lui souris et lui dis bonjour.

Je lui souris également, enfin si c'est une femme

je souris

Je souris aussi.

je lui répond de même, surtout si elle est charmante

En fonction du sexe, je réponds

Qu'est ce qu'il me veut...

je lui dis bonjour

Je me dis que je le connais

je me méfie