Active and passive voice

Active and passive.

• Active: the subject does the action: 'Early pioneers laid the foundation.'
• Passive: the subject receives the action: 'The foundation was laid by early pioneers.'

Same facts, different focus. The active puts the pioneers first; the passive puts the foundation first.

Active sentences are usually clearer and shorter. Use the passive on purpose, when:

• 1. the action matters more than who did it: 'A cure for the disease was discovered.'
• 2. the doer is obvious: 'The national anthem is sung at the beginning of the event.'
• 3. the doer is unknown: 'The car was stolen last night.'

Science writing uses the passive a lot, for reason 1: a result should not depend on who did the experiment.

• 'I conducted an experiment' → 'An experiment was conducted.'
• 'I placed various plants under different light conditions' → 'Various plants were placed…'
• 'I recorded data daily' → 'Data was recorded daily.'

How to form it: the right form of be + the past participle. Make 'be' agree with the new subject: 'Blood samples were taken' (plural); 'The amount was measured' (singular).

The Chandrayaan passage uses the present passive for each step: the spacecraft is launched towards the Moon from the Earth, is positioned, its path is adjusted, it is slowed down, and the rover is released.