There are two dogs and a horse under the tree 为什么要用are

Is,Are) there a dog and two cats under the tree? There is a cat and two dogs under the tree.一句有语法错误吗 改错（只有一处错误）There are a little dog and two cats under the tree There are two boys______(talk) under the tree. There are two boys_____(sit) under the big tree ______under the tree,There are two cats under it.横线中应填什么 A.W the two girls are reading under a tree? 1,There are a dog and a cat under the tree .2.Tom doesn't hi 填空：There ( ) a dog and a rabbit under the tree.( am ,is,are, There are a bear,a cat and two dogs at the zoo.在are、and、an中, There are two girls under the tree.They are singing.(合并为一句） There are five______(sheep)under the tree