He refused________overtime to spend the evening with his family.

The discovery was a major_____ for research workers.

What does the passage mainly discuss?

Which of the following could serve as the title for the passage?

The word “perceive”in paragraph 4 is closest in meaning to

Which of the following is NOT true, according to the passage?

We first have met each other in San Diego in 2018.

A.Therefore B.In addition C.However D.Although

What does the word "they" in paragraph 1 refers to_______.

What can be inferred from the extinction of the dinosaurs in paragraph 2?