％0期刊文章％a morice，alyn H.％t相关性和因果关系：covid-19 Conundrum％D 2020％r 10.1183/13993003.03174-2020％J欧洲呼吸杂志j欧洲呼吸杂志％p 2003174％p 2003174％v 56％v 56％n 4％u https：u https：u https：u https：//www.qdcxjkg.com/content/erj/56/4/4/2003174.full.pdf