1. (Varying) input, the firm can vary output.
2. There was an increase in the quantity of gas (produced) last
year.
3. The work of a farmworker and a nurse are measured in terms of
payment (received).
4. (Imposeing) some restrictions on food prices, governments
make it possible for all the people to buy enough food.
5. Firms producing computers act as buyers in the markets for
the services of computer programmers.