Uncountable or mass nouns such as gold, money, water, sugar, knowledge, information, advice, wood, iron, meat, spaghetti, butter, cheese, milk, tea, oil, air, oxygen, smoke, and rice use singular verbs.

Examples:

Air is more fresh in far provinces.

Gold has been discovered in South Africa.

Compound subjects joined by and use plural verbs.

Example:

Alan Arnold Griffith and Frank Whittle work with gas turbine engines.

Compound subjects that are closely related or that refer to the same person or thing use singular verbs.

Example:

My classmate and best friend is coming to dinner.

Compound subjects that begin with each and every use singular verbs.

Example:

Every discovery and invention propels humankind's standard of living to new heights.

Compound subjects joined by either-or or neither-nor use the verb that agrees with the subject nearest to the verb.

Examples:

Either the luxury liner or the jet planes take the passengers to Asia.

Neither the jet planes nor the luxury liner takes the passengers to Asia.