Machines were made to be man's servants. Yet, man has grown so (1)______ on them that they are in a fair way to become his (2)______. Already men spend most of their lives looking after and waiting (3)______ machines. Machines are very stern bosses. They must be fed with coal and (4)______ petrol to drink and oil to wash with and must be kept at an (5)______ temperature.
Select the most appropriate option for blank no. 4
Identify the most appropriate option to substitute the underlined segment. If no substitution is required, select No substitution. The shoebill stork can be recognise from its long legs and broad wings.