Skip to main content
20% off your first payment$5.99 for your first week, then $7.49 · Ends November 15, 2026See plans

Build a Sentence

Complex sentence with "because"

"Because" introduces a reason clause explaining why the main clause happened. It can come before or after the main clause.

6 worked examplesCompound Complex

The pattern

Main clause + BECAUSE + reason: She left BECAUSE she was tired.

Worked examples

6 shown

Word order shown is Reach120’s reading of standard English usage for this sentence. ETS does not publish a correct/incorrect judgement for individual items, and this is not an official score.

medium

Why are you tired?

The words you are given

  • was approaching
  • because
  • worked
  • quickly
  • overtime
  • and
  • I
  • the deadline

The order that works

I worked overtime because the deadline was approaching quickly.

medium

What happened to the flight?

The words you are given

  • traffic
  • severe weather
  • was delayed
  • The plane
  • disrupted
  • because
  • and
  • air

The order that works

The plane was delayed because severe weather disrupted air traffic.

medium

Why was she late?

The words you are given

  • missed
  • on this
  • and
  • She
  • since
  • the bus
  • particular morning
  • she overslept

The order that works

She missed the bus since she overslept on this particular morning.

hard

Why did the experiment succeed?

The words you are given

  • and
  • indicated
  • their methodology
  • design flaws
  • initial results
  • because
  • The researchers refined
  • several fundamental

The order that works

The researchers refined their methodology because initial results indicated several fundamental design flaws.

hard

Why did policies change?

The words you are given

  • and
  • graduates
  • practical technical skills
  • with stronger
  • because
  • The university updated
  • employers demanded
  • its curriculum

The order that works

The university updated its curriculum because employers demanded graduates with stronger practical technical skills.

hard

Why was the factory relocated?

The words you are given

  • manufacturer moved
  • because domestic
  • domestic
  • The
  • operating costs
  • increasingly prohibitive
  • production overseas
  • had become

The order that works

The manufacturer moved production overseas because domestic operating costs had become increasingly prohibitive.

Practice this pattern against the clock.

Try Build a Sentence

Reach120 is an independent practice tool. It is not affiliated with, endorsed by, or approved by ETS, and it does not provide official TOEFL® test scores.

TOEFL® is a registered trademark of ETS. This product is not endorsed or approved by ETS.