Not "These is my phone." — say "This is my phone.". 一个东西 → this（搭配 is），不是 these。
试一试: ___ is my phone. (one thing, in my hand) (This / These / That) 答案: This — 一个东西，而且离你很近 → this。"These" 是多个的时候用；"that" 是远的时候用。所以是：This is my phone.
that = 远 + 一个
一个 离你 远 的东西，用 that。
That is your car.
That building is tall.
I want that cookie.
Not "This is your car. (it is far away)" — say "That is your car.". 只要离得远 → 用 that，哪怕只是一个东西。
试一试: ___ building over there is tall. (That / This / Those) 答案: That — 一栋楼，离你很远 → that。"This" 会表示它离得近；"those" 会表示是多个。所以是：That building.
these = 近 + 多个
多个离你近的东西，用 these（也就是 this 的复数）。
These are my keys.
I like these flowers.
Try these shoes.
Not "This are my books." — say "These are my books.". 多个东西 → these（搭配 are），不是 this。
试一试: ___ are my keys. (right here in my hand) (These / This / Those) 答案: These — 多个东西，而且离你很近 → these。"This" 是一个的时候用；"those" 是远的时候用。所以是：These are my keys.
those = 远 + 多个
多个离你远的东西，用 those（也就是 that 的复数）。
Those houses are old.
Look at those birds.
Those are my friends.
Not "That houses are old." — say "Those houses are old.". 多个东西又离得远 → 用 those，不是 that。
试一试: ___ houses across the street are old. (Those / That / These) 答案: Those — 多栋房子，离得很远 → those。"That" 是一个的时候用；"these" 会表示离得近。所以是：Those houses.
试一试: Remember: one or many? ___ are my friends, over there by the door. (Those / That / This) 答案: Those — "Are" 告诉你是多个，所以一定是 these 或 those。"Over there" 告诉你离得远，所以是：Those are my friends.