A.www.pubmed.govB.www.pubmed.comC.www.pubmed.netD.www.pubmed.edu
A.colo?r d?op?lerB.colo?r d?oplerC.color d?op?lerD.colo?r dop?ler
A.aspirin OR asthmaB.aspirin AND asthmaC.aspirin NOT asthmaD.aspirin AND NOT asthma