Past perfect: แบบฝึกหัด

Complete the following sentence about a science experiment using the past perfect form of the verbs in brackets:
"The students observed that the eggshell (dissolve) ___ because the vinegar (react) ___ with the calcium carbonate."

In a report about a school assembly, which of the following options correctly uses the past perfect to describe the sequence of events?
"The principal (1. finish) ______ his speech by the time the guest speaker (2. arrive) ______ at the hall."

In a history report about the evolution of the English curriculum, describe the sequence of events using the past perfect for the earlier action and the simple past for the later action:
"By the time the new Language across the Curriculum (LaC) framework was officially implemented in 2010, the school committee (already, develop) ______ the necessary teaching resources."

Choose the correct sentence that uses the past perfect tense to show which action happened first in this Arts Education scenario:
Action 1: The museum guide explained the history of the painting.
Action 2: The students entered the exhibition hall.

Identify the sentence that uses the past perfect tense to explain the cause of a past result in a Science context.

Rewrite the following sentence using the past perfect tense to show that the first action was completed before the second one:
"The students (finish) their lab report before the science teacher (enter) the classroom."

Combine these two events into a single sentence using the past perfect for the earlier action and after:
Event 1: The choir practiced the hymn for two hours.
Event 2: They performed for the school assembly.

Rewrite the following paragraph by changing the bracketed verbs into the past perfect or simple past to show the correct sequence of events in a History lesson:

"The archaeologist (discover) ______ the ancient coins only after his team (dig) ______ at the site for over six months. He (be) ______ thrilled because he (never / see) ______ anything like them before."

Complete the sentence using the past perfect tense of the verbs in brackets:

"By the time the teacher distributed the reading materials, the students ___ (already / finish) reading the summary."

Read the following sentences written by a student and choose the option that correctly fills in the blanks using either the past perfect or the past perfect continuous:

"When the teacher checked the draft, Sarah (1) ______ (write) her essay for two hours, and she (2) ______ (complete) three pages."