He gave a talk______ the causes of dengue fever.
He gave a talk______ the causes of dengue fever.
Explanation
He gave a talk on the causes of dengue fever.
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we use the "on" preposition because we talk "on" causes of dengue fever
**
ND10-1-2023
He gave a talk on the causes of dengue fever.
***
we use the "on" preposition because we talk "on" causes of dengue fever
**
ND10-1-2023