Hi, everybody. 大家好！ I'm here at Children's National Medical Center in Washington, D.C., visiting with some kids being treated here all the time for asthma and other breathing problems. 此刻，我在华盛
Hi, everybody. 大家好！ I'm here at Children's National Medical Center in Washington, D.C., visiting with some kids being treated here all the time for asthma and other breathing problems. 此刻，我在华盛
