Lesson

Giving reasons: as, because, for and with

Causal connectors

≈ 15 min 8 block(s)

Text

Giving reasons: as, because, for and with

This lesson explains four common ways to give reasons in English and how to choose the correct connector or structure depending on what follows (a clause or a noun phrase) and the level of formality.

because → introduces a reason clause (subject + verb).
as → introduces a reason clause; often used in formal or written contexts and can appear at the start of a sentence.
for → as a coordinating conjunction meaning 'because' (more formal or literary); connects two clauses.
with → followed by a noun phrase to give background or reason ('With no budget, we postponed the campaign.').

Table

Connectors for giving reasons

Connector	Use	Example
because	Use before a clause (because + subject + verb). Neutral, common in speech and writing.	The launch was delayed because the tests failed.
as	Use before a clause; often formal and used to give background information. Can appear at the start.	As the client requested changes, we revised the proposal.
for	Coordinating conjunction meaning 'because'; connects two clauses; slightly formal or literary.	She resigned, for she disagreed with the policy.
with	Use with a noun phrase to present a circumstance or reason (with + noun phrase).	With a limited budget, the marketing team prioritized digital ads.
because of	Use before a noun phrase (because of + noun phrase) to explain reason.	The meeting was postponed because of heavy traffic.

Tip

Key rule: Match connector to structure

Decide if you need a clause (subject + verb) or a noun phrase, then pick the connector:

Use because / as / for + clause (e.g., because the team missed the deadline).
Use because of / with + noun phrase (e.g., because of the delay; with limited resources).
Put a comma before 'for' when it links two independent clauses (She left, for she was tired).

Formality: 'because' is neutral, 'as' and 'for' are more formal; 'with' is followed by a noun phrase.

Example

Examples in context

We delayed the launch because the tests failed.

As the client requested changes, we revised the proposal.

She resigned, for she disagreed with the policy.

With a limited budget, the marketing team prioritized digital ads.

Tip

Common mistakes to avoid

Watch for these universal errors when giving reasons:

Using 'because' + noun phrase instead of 'because of' (wrong: because the delay; correct: because of the delay).
Using 'as' at the end of a sentence or in informal speech where 'because' is clearer.
Using 'for' like a preposition (wrong: They left for rain) instead of as a conjunction or using 'because of'.
Using 'with' followed by a clause instead of a noun phrase (wrong: With he was late, we started without him).
Punctuation errors: forgetting the comma before 'for' when it connects two independent clauses.

Focus on clause vs noun phrase and on punctuation: these cause most errors.

Quiz

Choose the correct sentence:

Hint: Decide if you need a clause (subject + verb) or a noun phrase.

Quiz

Complete: The team postponed the meeting _____ heavy traffic.

Hint: Think about which form (because / because of / with) goes before a noun phrase.

Quiz

Choose the most natural sentence in business English:

Hint: Check whether the phrase after the connector is a clause or a noun phrase.

Key Points

GrammarPoint

because

conjunction CEFR A2 //bɪˈkəz//

Introduces a reason and is followed by a clause (subject + verb).

We canceled the meeting because the presenter was ill.

GrammarPoint

because of

prepositional phrase CEFR B1 //bɪˈkəz əv//

Used before a noun phrase to give a reason.

The flight was delayed because of technical problems.

GrammarPoint

as

conjunction CEFR B2 //æz//

Introduces a reason clause; often used in formal or written contexts and can appear at the start of a sentence.

As the vendor was late, we moved the meeting.

GrammarPoint

for

conjunction CEFR B2 //fɔːr//

A coordinating conjunction meaning 'because' that connects two independent clauses (somewhat formal or literary).

He apologized, for he had missed the deadline.

GrammarPoint

with

preposition CEFR A2 //wɪð//

Used before a noun phrase to present a circumstance or background reason (with + noun phrase).

With low sales this quarter, the company reduced expenses.

Vocabulary

reason

noun CEFR B1 //ˈriːzən//

A cause or explanation for an action or event.

The reason for the delay was a technical fault.