When the subject of a subordinate clause introduced by if, when, while, or although matches the main clause subject, English often drops both the repeated subject and to be, as in while walking home, she noticed the streetlight, or if necessary, call me.
Grammar Rule
When the subject of a subordinate clause (if, when, while, although) is the same as the main clause subject, English often drops both the repeated subject and to be, leaving only the conjunction plus a participle, adjective, or prepositional phrase. This only works when the omitted subject is identical to the main clause subject.
Ellipsis after If/When/While/Although with Participles: Rules and Examples
| Full form | Reduced form | Example |
|---|---|---|
| While she was walking home… | drop subject + was | While walking home, she noticed the streetlight. |
| If it is necessary… | drop it is | If necessary, call me. |
Remember: This ellipsis drops the repeated subject and to be only when the subordinate clause shares the same subject as the main clause — otherwise, state the subject and verb in full.
Practice Test
Instructions
Answer each question in the test below using ellipsis after if, when, while, and although correctly. You will get a new random set of questions every time you retake the test, plus a downloadable results summary with your name and score at the end.
C2-19 Ellipsis after If/When/While/Although with Participles
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Frequently Asked Questions
What gets dropped after if, when, while, or although?
The repeated subject and to be, as in while walking home, she noticed the streetlight.
What condition must be met for this ellipsis to apply?
The omitted subject must be identical to the main clause subject.
What does if necessary mean in full form?
If it is necessary.
What remains after the subject and to be are dropped?
The conjunction plus a participle, adjective, or prepositional phrase.