Apply semiotic analysis to three advertisements.
1 Print from WWF

Slogan is that before it is too late Our nature would breathe through its a pair of lungs. However, it is polluted and damaged that makes it brown. Keep the nature's lungs clean. Keep our nature clean.
1 TV from youtube - Doritos
Funny Advertisement
Only focus on 2nd part - Doritos
People may consider that a man who wear sunglasses and hold a blind stick would be totally blind.  However, there is different levels of blindness.
In the advertisement, the man may have a problem of visual, but not a blind.

1 outdoor sign from a public area

A circle with a crossing line means Don't
Picture in the circle is a cigarette which means Smoking
Therefore, overall, it is "Don't Smoking".
Whether there is a wording or not, people can get the message through semiotic