Five and nine is/are fourteen.为何既可用is,也可用are.求救阿!

Five and nine is/are fourteen.为何既可用is,也可用are.求救阿! What ________ four and five?______ nine.A.are,They are B.is, Fourteen and nine is twenty-three. Four and five _____ nine.A.are B.is C.am Nine and zero(is?are?make?)=nine Five and four is nine.句型转换 为什么nine and one 是is ten而不是are 一道英文数学题= There are five numbers.Their average is nine.If we What four and five?nine.A.are T Fourteen and fifteen are t____. five and three are eight .还是is eight five pounds is/are enough