Question

Chikungunya is a different virus, but it is spread by the same mosquitoes. Like dengue, it normally produces higher fevers and worse pain than Zika, which is one reason Zika outbreaks have sometimes gone unnoticed when dengue and chikungunya have been circulating at the same time.

Researchers are still not sure how the Zika virus made its way to Brazil. Some say it could have arrived during the World Cup in 2014, when Brazil welcomed players, fans and others from around the world. Others think the virus may have come during a canoe race weeks later, when paddlers from French Polynesia arrived in Rio de Janeiro. [The New York Times]

Chikungunya is…/ Reaserchers are… O emprego de formas diferentes do verbo to be (is/are) nos trechos acima ocorre porque:

‘Chikungunya’ (a doença) é feminino e ‘Reaserchers’ (os pesquisadores) é masculino.
‘Chikungunya’ é singular e ‘Researchers’ é plural.
‘Chikungunya’ é neutro (coisa) e ‘Reasearchers’ são pessoas.
‘Chikungunya’ é objeto e ‘Researchers’ é sujeito.
O autor do texto prefere assim.

Answer 1

'Chikunguya' é singular e 'Researchers' é plural.