For
practical English, just look at YY English.
Today is a national day of mourning for those lost to the coronavirus.
national mourning National mourning. mourn [mɔːn] Mourning
Note that it is mourning, not morning
Tomb Sweeping Day Tomb Sweeping Day
succumb [səˈkʌm] Unable to resist disease/temptation (here refers to death due to the epidemic)
succumb to Fixed collocation
Those who succumbed to the novel coronavirus.
martyr Martyrs [ˈmɑːtə(r)]
half-mast flags at half-mast
lowered to half-mast, or fly at half-mast, flags lowered to half-mast
pay tribute to those heroes.