Tenses in question tags：練習問題

Read the following sentence and choose the correct question tag:
"They have already finished their science project, ______?"

Which of the following sentences correctly applies a question tag to the Past Perfect Tense?

Read the following sentence which describes a scientific observation:

"The chemical solution in the beaker has turned cloudy after the reaction, ______?"

Choose the correct question tag to complete the statement.

Determine the correct question tag for a sentence describing a past event in a History report:
"The explorers found no evidence of previous settlements on the island, ______?"

Complete the sentence with the appropriate question tag:
"The students were practicing their listening skills in the lab, ______?"

Provide the appropriate question tag for the following statement:
The school assembly has already started, _______?<\/b><\/p>

Determine the correct question tag for the following statement involving the present perfect tense and a negative adverb:
The teacher has never punished a student for making mistakes, _______?<\/b><\/p>

Identify the correct question tag for the following future perfect tense statement:
By next month, the students will have finished the entire writing curriculum, _______?<\/b><\/p>

Read the following statement about a Science experiment and answer the sub-questions below:

"Neither the lead researcher nor his assistants were aware that the chemical reaction had already completed."

a) Provide a suitable question tag for the statement above.

b) Explain the grammatical rules regarding the polarity (positive/negative) and the subject pronoun used in your tag based on the presence of the word 'Neither'.

In an academic report about Science, a student writes:

"The solution will have dissolved the eggshell by the end of the 48-hour period, ______?"

a) Identify the exact tense used in the main clause.
b) Provide the correct question tag for this sentence.
c) If the student changed the sentence to: "The solution hardly dissolved the shell, ______?", what would the new tag be? Explain the change in polarity.