Units of measurement as modifiers

PART 1: Number + unit of measure (singular)+ noun

When a number followed by a unit of measure comes before a noun, the unit of measure is used in the singular.

Cf: The talk lasted three hours.

It was a three-hour talk.

Notice that a hyphen is used only when the number and the unit of measure come before the noun.

Cf: A three-day course

The course lasted three days.

• The hyphen is used between the number and the unit of measure, NOT between the unit of measure and the noun.

RIGHT: a thirty-minute meeting

WRONG: a thirty-minute-meeting

Paraphrase the sentences using a unit of measure before the noun as

in the example.

Example:

1) The presentations that take ten minutes will come right after the introduction.

The ten-minute presentations will come right after the introduction.

2) Notes of five pounds are scarce.

Solution:

Five-pound notes are scarce.

3) The course consists of six lessons of two hours.

Solution:

The course consists of six two-hour lessons.

4) He has a baby who is three months old.

Solution:

He has a three-month-old baby.

(Notice that here two hyphens are necessary because both “month” and “old”

make up the unit of measure.)

5) We need a can of five litres.

Solution:

We need a five-litre can.

PART 2: Measurement of time

The ‘s structure (or the plural with s’) is often used to say how long things last. Notice that hyphens are not used when we use ‘s or s’:

a days’ journey (wrong: one day’s journey)three hours’ journeytwenty minutes’ delay

An expression with a hyphen (see part 1) is also possible here: a three-hour journey, a twenty-minute delay

Correct the mistakes

1) There’s a two-miles walk from our hotel to the conference centre.

Solution:

There’s a two-mile walk from our hotel to the conference centre.

2) I prefer to take a taxi because I am carrying a five kilo’s bag.

Solution:

I prefer to take a taxi because I am carrying a five-kilo bag. (kilo is not a unit of time)

3) We’ll attend a two-hour-meeting.

Solution:

We’ll attend a two-hour meeting (or two hours’ meeting)

4) Then, there’ll be one two-hour break.

Solution:

Then, there’ll be a two-hour break.

5) After that, we’ll meet again for a fifty minute’s plenary session.

Solution:

After that, we’ll meet again for a fifty minutes’ plenary session.(or fifty-minute plenary session)