<p>many crops (have been) (heavily) damaged this year by severe rainstorms (when passing) through the rural provinces.</p>
<p>the error in (when passing), choice D</p>
<p>Can any one explain why and the grammatical rule for it. </p>
<p>Thanks :)</p>
<p>Many crops (have been) (heavily) damaged this year by severe rainstorms (when passing) through the rural provinces.</p>
<p>The intent of the writer is to clarify the noun “rainstorms” – i.e. which specific rainstorms? The standard way to do that in English is through a clause that starts with either “that” or “which”. “That” is used when the the clarification is essential (“restrictive”), and “which” is used when the clarification is non-restrictive. A non-restrictive clarification is one that can be left out without changing the essential meaning of the sentence.</p>
<p>In the above example we are talking about specific rainstorms – ones that passed through the provinces.</p>
<p>So:
Many crops have been heavily damaged this year by severe rainstorms that passed through the rural provinces. (Note that an alternative to “passed” in this particular sentence is “had passed”.)</p>
<p>Note: that and which are pronouns. Here they refer to “rainstorms”.</p>
<p>In the original “when passing” both the use of the adverb “when” and the participle/gerund “passing” are wrong. The adverb is misused and “passing” is ambiguous. It’s unclear what “passing” means or refers to.</p>