Do You Know Why We Can’t Say “这些本书 (zhè xiē běn shū)”?

“这本书(zhè běn shū)” and “这些书(zhè xiē shū)” is different.

“This book” and “These books”

We can't say:
这些本书都是我的。
Zhèxiē běn shū dōu shì wǒ de.
These books are all mine.

“本(běn)” is a measure word, and “些(xiē)” is a measure word too.

There is only one measure word between “这(zhè)” and “书(shū)”, and two measure words cannot be used.

“这本书(zhè běn shū)”=“这一本书(zhè yì běn shū)”, this book is singular;“这些书(zhè xiē shū)” These books are plural.

For example:

1)   a这个人是我朋友。
Zhège rén shì wǒ péngyǒu.
This man is my friend.

b.这些人都是我朋友。
Zhèxiē rén dōu shì wǒ péngyǒu.
These people are all my friends.

2) a.这辆行车是新的。
Zhè liàng zìxíngchē shì xīn de.
This bike is new.

b.这些自行车都是新的。
Zhèxiē zìxíngchē dōu shì xīn de.
These bikes are all new.

3)a. 这张是上海地图。
Zhè zhāng shì shànghǎi dìtú.
This is a map of Shanghai.

b. 这些都是上海地图。
Zhèxiē dōu shì shànghǎi dìtú.
These are all maps of Shanghai.

4）a. 这个包子很好吃。
Zhège bāozi hěn hào chī.
This bun is delicious.

b. 这些包子很好吃。
Zhèxiē bāozi hěn hào chī.
These buns are delicious.

5）a. 那朵花非常漂亮。
Nà duǒ huā fēicháng piàoliang.
That flower is very beautiful.

b. 那些花非常漂亮。
Nàxiē huā fēicháng piàoliang.
Those flowers are very beautiful.

6）a. 他不打算养那一只动物。
Tā bù dǎsuàn yǎng nà yī zhǐ dòngwù.
HE is not going to have that animal.

b. 他不打算养那些动物。
Tā bù dǎsuàn yǎng nàxiē dòngwù.
He's not going to have those animals.

7）a. 这个学生种了一棵树。
Zhège xuéshēng zhǒngle yī kē shù.
The student planted a tree.

b. 这些学生种了这些树。
Zhèxiē xuéshēng zhǒngle zhèxiē shù.
The students planted the trees.