Wrong comparison

Mistakes are often made by students when they construct sentences involving comparison. The following are a few examples of such mistakes:

1 My book is better than you. [wrong]
My book is better than yours. [correct]
[In the first sentence, you are comparing a book to a person which is wrong whereas in the second sentence, my book is compared to your book (yours refers to your book)]

2 The facilities in town are better than the country side. [wrong]
The facilities in town are better than those in the country side. [correct]
[In the first sentence, facilities are compared to country side which is is wrong. However, in the second sentence, the comparison is correct because facilities in town are compared to facilities in the country side (those refers to facilities).]

3 The shirt I bought is cheaper than you. [wrong]
The shirt I bought is cheaper than yours. [correct]
[In the first sentence, shirt is compared to you, a person. Hence it is wrong. On the other hand, shirt is compared to shirt (yours refers to shirt) in the second sentence.]