This is increasingly becoming less common based on newer data points and there are numerous theories on why applicants are only allowed one card. (uponarriving.com)
Although there have been numerous theories as to what might predict a longer recovery time, there is no definitive answer as to why it takes some children longer to recover. (sciencedaily.com)
Numerous theories exist about why girls often lose confidence and interest in math and science during their secondary school years. (edutopia.org)