Language structure
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Describing ProcessesWhile describing processes, passive voice can be used because the action (agent) is more important than the person doing this action.
- Simple present passive: Agent +is/are + Ved/3
- e.g. When a chemical reaction occurs, energy is transferred to or from the surroundings. (energy (agent) + is + transferred).
- e.g. In an endothermic reaction, heat is absorbed from the surroundings. (heat (agent) + is + absorbed from).
- e.g. The standard enthalpy change of combustion is the enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions. (a substance (agent) + is + burnt).
- Modal passive:can + be +Ved/3
- e.g. Hess’s law can be used to calculate enthalpy changes for reactions that do not occur directly or cannot be found by experiment. (Hess’s las (agent) + can + be+ used), (reactions (agent) + cannot + be + found).