these是this的复数吗?

these是this的复数吗? those,that,these,this的用法真的是these,those用于单复数都可,而that,this只能用于单数吗?要给出依据, 一般疑问句单数变复数的变化Is this His coat变成复数可不可以是 Are these his coats,还有 Is this your coat变成复数是 Are these your coats而不是Are these these coats.变化规律是什么, these是 的复数形式 these的复数是什么 this复数 是those吗? Phenomena是phenomenon的复数形式,前面跟this 还是 these?后面跟is还是are?期待权威人士解答This unusual phenomena is worth paying attention to. 请问单数句变复数句,句中的人称代词跟着变吗?例如：This is my friend,在变为复数句时,是These are my friends还是These are our friends? This is my sister 改为复数句是These are my sisters还是These are our sisters This is a box.(改为复数句）是These are boxes.还是These are many boxes. this is a cat变复数是these is.还是they is. 看了一遍单数变复数的形式的规则,this的复数为什么是these求教, 指示代词及其复数形式的用法this,that;these,those 英语里问颜色有复数和单数,想问下单数时回答,the,that,these,this,those等词是怎么用的,在哪用的 that、this只能用单数,those、these只能用复数吗? those 是this 的复数形式么 what's that?(those)、This is a dog.（these）、He's a teacher.（they）、is this a new bookwhat's that?(those)、This is a dog.（these）、He's a teacher.（they）、is this a new book（these）改复数 括号里的是提示 this is my feet 还是these are my feet在百度翻译里查这是我的脚,结果发现写的是This is my feet,但是This后面不是只能用单数,这里却用复数,怎么回事?