Past perfect continuous: แบบฝึกหัด

In a narrative about a school project, which sentence correctly uses the past perfect continuous to emphasize duration before a past action?

Fill in the blank with the most appropriate past perfect continuous form:

Before the school board made the final decision, the principal ___ (consider) several different e-learning platforms for nearly a month.

In an essay about educational technology, a student writes:

"The school ___ (use) traditional printed materials exclusively until the IT coordinator introduced the new e-learning platform in 2017."

Which past perfect continuous form is most appropriate?

In a story about a student's dedication, which form correctly fills the blank?

"By the time the competition results were announced, Sarah ___ (study) the history of the English language for over a year."

Which of the following sentences correctly applies the past perfect continuous to show the cause of a past situation in a Language across the Curriculum (LaC) report?

"The group's discussion was extremely productive because they ___ (gather) information from various online sources before the meeting began."

Combine the following two observations from a Science experiment into a single sentence using the past perfect continuous and the word before to show the duration of the first action:
1. The students waited for the chemical reaction for twenty minutes.
2. The mixture finally turned blue.

In an inter-disciplinary Science and English project, students recorded the following observation:

"The students ___ (observe) the chemical reaction for over an hour when the liquid suddenly changed color from clear to bright blue."

Complete the sentence using the correct form of the past perfect continuous.

In a Personal, Social and Humanities Education (PSHE) report, describe a long-term action that was interrupted by another event. Use the past perfect continuous:

"The geographers (conduct) ______ soil tests for several hours before the heavy rainstorm forced them to return to the bus."