来自李广宇的问题
Thefamily__atthelunchtablewhensomeonecametotellthemwhathadhappenedat__.A.weresitting;MrBrownB.weresitting;MrBrown'sC.wassitting;MrBrownD.wassitting;MrBrown's解析上题,并问：family什么时候用单数什么时候用复
Thefamily__atthelunchtablewhensomeonecametotellthemwhathadhappenedat__.
A.weresitting;MrBrownB.weresitting;MrBrown's
C.wassitting;MrBrownD.wassitting;MrBrown's
解析上题,并问：family什么时候用单数什么时候用复数
