When to Use The Present Perfect Tense
Summarizing previous work
- Many researchers have investigated the effects of poverty on health.
- Studies have shown a link between cancer and red meat consumption.
When mentioning research that took place over an unspecified time period in the past
- Green et al. have conducted extensive research on the ecological effects of wolf reintroduction.
Emphasizing the present relevance of previous work
- Smith (2015) has found that younger drivers are involved in more traffic accidents than older drivers, but more research is required to make effective policy recommendations.