article_snippet.sent: Most have never been seen since, except in a photograph in which the girls sat on the ground in a semi-circle, clad in Islamic dress.
article_snippet.sent: the girls were between 16 and 18 years old.
article_snippet.sent: On Twitter, a hashtag began trending and spread around The world: #BringBackOurGirls.
article_snippet.sent: On Tuesday, Malala Yousafzai, the 17-year-old Pakistani girl who was shot in the face for speaking out in favor of girls' education, sent a message to girls'.
article_snippet.sent: Each of girls' has had a birthday in captivity.
article_snippet.sent: And Tuesday on Twitter, a hashtag was still trending: #BringBackOurGirls.
highlights_snippet.sent: World still expresses hope that the girls will return .
  