Piece words make it possible to talk about a single unit or units of something which is seen as uncountable. Piece words include words such as piece, bit, item, article. We normally use them with of. We can use them in the singular or the plural.
with a piece word
The piece words combine (collocate) with nouns in different ways. Here are the most common combinations. The piece words are arranged from the least formal (bit) to the most formal (article).
fun, luck, time, work, paper, information, bread, money, news, gossip
paper, software, information, work, writing, furniture, wood, equipment, music, cloth, land
clothing, equipment, furniture, food, information, interest, business, jewellery, news
furniture, clothing (article is the least common piece word and is rather formal. It combines mostly with these two nouns).
This is a new piece of equipment which helps rescuers find earthquake victims trapped in buildings.
a new equipment…
I had a bit of luck the other day – an old friend offered me a job!
I had a luck…
Three items of jewellery were stolen from Miss Hart’s dressing-room.
Every article of clothing must be marked with the child’s name.
There are also more specific piece words which combine with particular nouns:
a drop of water, a drop of milk, a slice of bread, a loaf of bread, a bar of chocolate, a bar of soap, a pinch of salt
You will find these and more examples in a good learner’s dictionary.
Group words (sometimes called collective nouns) are nouns which refer to groups of people, animals or things. There are special group words for particular combinations of people, animals and things:
flowers (and types of flowers such as roses, tulips), grapes, cherries (and other similar fruit), keys
people, onlookers, admirers, protesters, shoppers
sheep, birds (and types of birds such as pigeons, geese)
workers, kids, youths, teenagers, thieves, criminals
(can be used with most nouns)
sheep, cattle, cows, goats (and similar animals)
wolves, dogs, hyenas, cards, lies
glasses, cups, plates, keys, tools (and other objects which form a group because they share the same features), rules, standards
fish (and types of fish such as herring, cod)
bees, flies, ants (and other insects)
scientists, researchers, experts, designers, detectives
Group words take a singular verb when they are used in the singular, and a plural verb when they are used in the plural:
A team of experts was called in to investigate the problem.
There was a flock of about 30 sheep in the field.
Gangs of youths were fighting one another in the streets.
There were swarms of flies everywhere.
Sometimes, singular group words are followed by a plural verb, but some people may consider this to be incorrect:
The committee produced a set of rules that were intended to prevent people from abusing the system. (or … a set of rules that was intended …)
I found a bunch of keys on the floor. Are they yours?