there 是副词,"在那里,在那儿"的意思.
一般的搭配是 there is / are
there is + 单数名词
there are + 复数名词
eg:1.There is one student in the classroom.
2.There are many students inthe classroom.
these ”这些” 与 those"那些”相对,后面一般接复数名词．
They "他们”人称代词,一般做主语,如
They are teachers.