serious

a.严肃的；严重的；认真的

serenade, serendipity, serene, serenely, serenity, serf, serfdom, serge, sergeant, sergeant-major, Sergt (also Sgt), serial, serial number, serialization, serialisation, serialize, serialise, serially, seriatim, series, serif, serio-comic, seriously, seriousness, serjeant-at-arms, sermon, sermonize, sermonise, serous, serpent, serpentine, serrate, serrated, serration, serried, serum, servant, serve, serve as, serve one's turn, serve right, server, service,