sit in forsb
—phrasal verbwithsitverbuk/sɪt/us/sɪt/present participlesitting|past tense and past participlesat
to take theplaceof someone who wouldnormallydo aparticularjobor go to aparticularmeeting
代替（某人）履行职责；代（某人）出席会议
Mr Baker isilltoday, soMissDixon issittingin for him (asyourteacher).贝克先生今天病了，因此由狄克逊小姐替他（上课）。