Learn English – Usage of “when” followed by verb+ing

grammaticalitypresent-participles

Is it okay to use "when" immediately followed by a verb ending with -ing?

For example:

  • When climbing the hill,…
  • When writing a book,…

Best Answer

The construction when + -ing form + complement is acceptable, and very common in written English. It is not often encountered in spoken English, however, which generally prefers a finite clause:

  • When climbing the hill they discovered an ancient footpath.
  • When they were climbing the hill they discovered an ancient footpath.

Be careful in using this construction that you do not create a dangling participle. The implied subject of the verb must be the same as the clause to which the when-clause is subordinated.

ok When climbing the hill they discovered an ancient footpath. ...
∗  When climbing the hill, John stayed behind to explore the ruined hut.

∗  marks an utterance as unacceptable.

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