Modal verbs：练习题

Select the most appropriate modal verb to complete this polite request:
"________ you please help me carry these heavy books to the library?"

Identify the sentence where the modal verb 'may' is used to express permission rather than possibility.

Evaluate the use of modal verbs in the following social contexts. Which sentence correctly uses a modal verb to express absence of obligation?
"Since the museum entrance is free today, you ________ pay for a ticket."

Complete the following sentence with the most appropriate modal verb to express a suggestion for a school event:

"We _________ organize a book fair to increase students' interest in reading."

Choose the modal verb that best expresses logical necessity or a strong obligation based on the context of school rules:
"To ensure safety, all students ________ register at the front desk before entering the laboratory."

Identify the modal verb used to provide a suggestion in the following sentence:
"The government can make better use of the land through careful planning."

Compare the use of modal verbs in these two instructions. Which one expresses a requirement and which one expresses a possibility?
1. You must wear goggles in the lab.
2. The experiment may be improved by using larger beakers.

Transform the following modal sentence into the passive voice:
"Students must submit their assignments through the e-platform."

Read the following safety instruction:
"Students should not mix these two chemicals without supervision, as an explosion could occur."

(a) Rewrite the first clause in the passive voice.
(b) Explain the difference in function between the modal verb "should" (in the negative form) and "could" as used in this instruction.

Consider the following sentence: "The researchers must have completed the lab report before the deadline."

(a) Rewrite this sentence in the passive voice.
(b) Explain how the meaning of the modal verb changes if "must have completed" is replaced by "might have completed" in the passive structure.