The phrase "advertisements may have" is correct and usable in written English.
You can use it when discussing the potential content or characteristics of advertisements.
Example: "Advertisements may have a significant impact on consumer behavior, influencing their purchasing decisions."
Alternatives: "ads might contain" or "advertisements could include".
For all of their impact, televised political advertisements may have reached the limits of their power.
But while the number of advertisements may have dipped, there has been a "proliferation" of eco-labeling, according to Scott McDougall, the president of TerraChoice, who says there are both good and bad players in the eco-labeling game.
The transparent roofs mean that rooftop advertisements may have to be moved, possibly to the sides of the taxis, said the Taxi and Limousine Commission commissioner, David S. Yassky.
And whatever limitations banner advertisements may have on the Internet, they are Hollywood productions compared with the possibilities on a cell phone screen that shows four lines with a maximum of 22 text characters a line.
Within the HBM and KAP models, these advertisements may have improved knowledge of harmful effects of smoking (perceived severity) but were limited in promoting self-efficacy that may spur the smoker to quit.
Furthermore, although we attempted for neutral wording in our advertisements, emphasizing the stress reduction aspect, our recruitment procedure by means of advertisements may have partially attracted a subset of people interested in this form of intervention, limiting the generalizability to the general population.
(Mr. Moylan said the Beard work chosen to illustrate the advertisement may have had something to do with this. It is called "The Power of Death". It features a white-robed man with a death skull for a head body-slamming a fierce saber-toothed tiger onto the body of a fallen elephant).
Third, the use of a sample of patients responding to an advertisement may have introduced sampling bias.
The recruitment procedure i.e., newspaper advertisement may have resulted in recruitment of participants who were motivated to exercise and this could bias the results.
And now that advertisers can measure the effectiveness of advertisements, they may have realised they were paying too much.
An additional, non-mutually exclusive possibility is that the advertisement call may have been under more selective pressure due to interference from environmental background noise [ 51].
