DATESUBDATE(A3, B3, "d") + "天" + mod(DATESUBDATE(A3, B3, "h"), 24) + "小时" + mod(DATESUBDATE(A3, B3, "m"), 60) + "分钟" + mod(DATESUBDATE(A3, B3, "s"), 60) + "秒"

if(DATETONUMBER(a3)<DATETONUMBER(b3)&&DATESUBDATE(A3, B3, "d")>0,"-","")+DATESUBDATE(A3, B3, "d") + "天" +
if(DATETONUMBER(a3)<DATETONUMBER(b3)&&mod(DATESUBDATE(A3, B3, "h"), 24)>0,"-","")+mod(DATESUBDATE(A3, B3, "h"), 24) + "小时" +
if(DATETONUMBER(a3)<DATETONUMBER(b3)&&mod(DATESUBDATE(A3, B3, "m"), 60)>0,"-","")+mod(DATESUBDATE(A3, B3, "m"), 60) + "分钟" +
if(DATETONUMBER(a3)<DATETONUMBER(b3)&&mod(DATESUBDATE(A3, B3, "s"), 60)>0,"-","")+mod(DATESUBDATE(A3, B3, "s"), 60) + "秒"
