Strategy is the most important thing in the examination. (Comparative)

No answer in the exam should be elaborated unnecessarily. (Active)

= We should not elaborate any answer in the exam unnecessarily.

When a student gets the question paper, he should read it attentively. (Simple)

= Getting the question paper, a student should read it attentively.

Initially the questions may seem difficult. (Negative) 

= Initially, the questions may not seem easy.

A student should try to answer all the questions to do good in the exam. (Complex)

= A student should try to answer all the questions so that he can do good in the exam.

If a student answers all the questions correctly, he will get good marks. (Simple)

= By answering all the questions correctly, a student will get good marks.

A student should not write irrelevant answers. (Affirmative)

= A student should write relevant answers.