Encuentra el sujeto real: ignora lo que va entre comas y los grupos con “of…”.
Posesivo plural: researchers’ (solo apóstrofo). Posesivo singular: researcher’s. Its = de él/ella (cosa); it’s = it is.
Una frase introductoria (“Walking to school, …”) debe ir seguida de quien realiza la acción.
Estrategia paso a paso
Lee la frase con cada opción en voz baja y busca pistas de tiempo (“in 1969”, “by the time”, “since”).
Nombres colectivos (council, team, committee) son singulares: its, has.
Trampas habituales
Concordar el verbo con el sustantivo más cercano en vez de con el sujeto.
Frases invertidas: “Beside the door stand two chairs” (el sujeto, “chairs”, va después del verbo).
Ejemplo resuelto
“The list of ingredients is long.” → el sujeto es “list” (singular), no “ingredients”.
Preguntas de ejemplo
Intenta responder antes de abrir la solución. Las preguntas están en el idioma del examen.
Pregunta 1
Dificultad fácil≈ 1 min
Last spring, the city ______ a program that pays residents to replace their lawns with drought-tolerant plants. So far, more than 2,000 households have signed up.
Which choice completes the text so that it conforms to the conventions of Standard English?
AA. launches
BB. will launch
CC. launched
DD. is launching
Ver respuesta y explicación
Respuesta correcta: C. launched
Explicación
“Last spring” places the action in the past, and households “have signed up” since then, so the program has already begun. The simple past “launched” fits.
“Launches” and “is launching” are present tense, and “will launch” is future; none fits an action completed “last spring.”
Pregunta 2
Dificultad media≈ 1 min
After a series of spring floods, state engineers inspected the forty-two bridges in the river valley and found that most of ______ needed only minor repairs.
Which choice completes the text so that it conforms to the conventions of Standard English?
AA. it
BB. its
CC. them
DD. their
Ver respuesta y explicación
Respuesta correcta: C. them
Explicación
The pronoun refers to “the forty-two bridges,” a plural noun, and it is the object of the preposition “of.” The plural object pronoun “them” is correct.
“It” and “its” are singular. “Its” and “their” are possessive forms, which would need a noun after them (“their bridges”).
Pregunta 3
Dificultad difícil≈ 2 min
The discovery of thousands of clay tablets inscribed with records of grain shipments, taxes, and loans ______ historians to reconstruct the economy of the ancient city in remarkable detail.
Which choice completes the text so that it conforms to the conventions of Standard English?
AA. have allowed
BB. allow
CC. are allowing
DD. has allowed
Ver respuesta y explicación
Respuesta correcta: D. has allowed
Explicación
The subject is “The discovery,” which is singular; “of thousands of clay tablets inscribed with records …” is a long modifier between the subject and the verb. The singular verb “has allowed” agrees with the subject.
“Have allowed,” “allow,” and “are allowing” are plural forms that would agree with “tablets” or “records,” not with the actual subject.