Making Venn diagram
All books are pen
Conclusion:
Some pens are book
Some books are pen
No books are pen
Conclusion:
No pens are book
Some books are pen
Both book & pen
Conclusion:
Some pens are book
Some books are not pen
Conclusion:
Not conclusion
Now boldly statement of syllogism is divided in three part
 Positive
 Negative
 Possibly
Positive part
All and some
Example: All books are pen. All pens are copy.
In this type of question you have to prove statement wrong. If you not prove it this means that this is true.
Suppose from above diagram we have to find out ‘No book are copy’ but we can prove it wrong. So it statement is not followed.
Negative part
No book is pen
In negative part we have to prove the statement right if we cannot prove it this means this statement is followed or true.
Statement: All books are pen. No pen is copy.
Conclusion: No book is copy.
Or book, pen copy
For using above two statements we cannot prove above conclusion right. So it follows.
Possibly part
In this type of part we have to make all possibility and if one of the thing say that it is possible then our conclusion become true otherwise wrong.
Statement: All books are pen.
Conclusion: All pens are book possibly Or,
It is possible all pen are book.
Now there will be two possibilities. One is that both book and pen are overlap. When both are overlapping then our conclusion will be right, it will follow.
At least statement
This statement is same as some statement
Complementary pair
Some time pair of statement came like
 no boy are student and
 some boy are student
See carefully these are only two case and one of the must follow so generally when these type of question came we can mark one of them right.
Some not statement
“Some not’ is opposite to “All” type statement if “All” being true then some not being false, and vice versa.
Statement: Some A are B.
No B are C.
Conclusions: I. Some A are not C.
II. Some C are not A.
1^{st} Conclusion is Some A are not C. for finding it we have to find out is it possible that All A re C if it is possible then conclusion is false otherwise true.
Now Venn Diagram is
We cannot prove that All A are C because some part of A which is b, is never be C.
Now from II: We have to prove that All C are A from following diagram
So it cannot be follow.
So in short if it given some A re not B you try to prove it that All A are B. If you can prove it then Some “A are not B” will not follow and vice versa.
The theory above may be summarised as:
If the type of the given proposition is 
Then the pictorial representation is 

A All S are P 
Always 

E No S are P 
Always 

I Some S are P 
Either 
Some S are P {Some S are not P} 
Or, 
Some S are P {All S are P} 

Or, 
Some S are not P {All S are P} 

O Some S are not P 
Either 
Some S are not P {Some S are P} 
Or, 
Some S are not P {All are P} 

Or, 
Some S are not P {No S are P} 