Confusing Pair of Noun

Rule 1

If a preposition comes after a noun and then the same noun is repeated, the noun should be used in singular form.

Example

• Ship after ship is arriving.
• He enquired from door to door.
• Row upon row of marble looks beautiful.
• Town after town was devastated.

Rule 2

Scenery, Hair, Information, Advice, Furniture, Poetry, business, mischief, Bread, Stationery, Crockery, Luggage, Baggage, Postage, Knowledge, wastage, Jewellery, Breakage, Equipment, Evidence, Work (works means literary pieces), New, percentage, Dirt, Dust, Traffic, Electricity, Music, Confectionery, Pottery,Bakery, Behaviour, Word (when used in sense  of discussion) Fuel and Cost are uncountable nouns and hence will take singular verb. These nouns will not take article ‘A/An, ‘many’, ‘few’, number of and ‘plural form’.

Example

• The scenery of Kashmir has enchanted us.
• The mischief committed by him is unpardonable.

Rule 3

When the words-score, dozen, hundred, thousand etc, are preceded by any other word denoting number,  they take no plural form. For example, look at the following sentences:
Example

• He has three dozen pencils.
• Sachin made two hundred runs.

->But when they are not preceded by any word denoting number they take plural form.

For example,

• Scores of people were there.
• Hundreds of men were arrested.
• Thousands of boys assembled to hear the speech
• Dozens of seats are vacant.

Rule 4

• Some nouns have the same form for the plural as well as for the singular. For example, the following are some nouns that belong to this category.
• Sheep, deer, species, aircraft, offspring, yoke, space, craft, salmon, hair, apparatus, series, fish, crops, swine, gross, means (way) etc.
• The number of the above words should be distinguished bytheir preceding adjectives/articles if the preceding words (these, those, ten, twenty etc) indicate plurality.

For example,

• Two deer were caught.
• Many sheep are grazing in the field.
• He has made a series of mistakes.
• Every means has been tried.
• Ram is using an apparatus.
• The apparatus kept in the science laboratory are new.

Rule 5

Physics, Economics, ethics, Mathematics, News, Innings, Politics, Summons, Mumps, measles, Rickets, shingles, Billiards, Athletics, Linguistics are certain nouns that are plural in form but singular in meaning. They take singular verb

Example

• No news is good news.
• Politics is a dirty game.
• Ethics demands honesty.
• Economics is an interesting subject.

Rule 6

Cavalry, cattle, infantry, peasantry, poultry, children, police gentry and people are certain nouns that are singular in form but plural in meaning. They take plural verb.
Example          

• ‘s’ is never used with these nouns.
• Police have arrested the thieves.
• Our infantry have marched forward. Cattle are grazing in the field.