This question is concerned with the supply of oil for central heating. In each case consider whether there is a movement along the supply curve (and in which direction) or a shift in it (and whether left or right):

(a) new oil fields start up in production;

(b) the demand for central heating rises;

(c) the price of gas falls;

(d) oil companies anticipate an upsurge in the demand for central-heating oil;

(e) the demand for petrol rises;

(f) new technology decreases the costs of oil refining; (g) all oil products become more expensive.