Multiple choice

Directions: Choose the option which is grammatically correct and the best version of the underlined part. On each table stood a couple of glass jars and guinea-pigs upon which the students were working and down the side of the room were slides bearing bleached dissections.

  1. guinea-pigs upon which the students were working

  2. guinea-pigs upon which the students had worked

  3. guinea-pigs upon which the students had been working

  4. guinea-pigs upon which the work still continued by the students

  5. guinea-pigs upon which the students worked
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Correct; the tense is correctly used as the action which started in the past still continued.

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