Question

is this your eraser？ no，it's theirs erase

哪儿错了？

Answer 1

-Is this your eraser? -No,it's theirs erase.应改为：
1.-Is this your eraser? -No,it's their erase.或
2.-Is this your eraser? -No,it's theirs .
理由
形容词性物主代词their 起形容词的作用，用在名词前erase。类似用法如

1. This is my book. 　这是我的书。
2. We love our motherand. 　我们热爱我们的祖国。
名词性物主代词 theirs起名词的作用，所以后面省掉eraser。又如
1. Look at the two pencils. The red one is yours and the blue one is mine.
看那两支铅笔，红色的是你的，蓝色的是我的。
2. He likes me. He doesn’t like her.
他喜欢我。不喜欢她。

Answer 2

theirs指的是他们的东西，已包涵物
他们的橡皮应该不止一块，再根据前面的提问知道是一块橡皮，所以应该是他的橡皮吧。
is this your eraser?
no,it is his eraser/no,they are their eraser.

Answer 3

theirs 去掉s,
their是“他们的”意思，不用加“s”了。

满意请采纳！！！

Answer 4

把最后的eraser去掉，theirs是名词性物主代词，后面不用加名词
不懂得欢迎追问，望采纳谢谢

Answer 5

theirs = their erase
重复了