stand的过去式( )see第三人称单数( )ride现在分词( )hippo复数( )on反...答:standed sees riding hippo是hippopotamus的缩写,参照下面第3点.1.以O结尾的词,许多加es构成复数,特别是一些常用词如:heroes,potatoes,tomatoes,echoes,tornadoes,torpedoes,dominoes,vetoes,mosquitoes,Negroes,mangoes,buffaloes,volcanoes 但下面几类词只加s:1.以“元音+o”或“oo”结尾的词如:videos...