How long could divers stay underwater in Halley's bell?
C
Những thợ lặn có thể ở dưới nước bao lâu trong cái chuông của Halley?
A. một vài giây
B. một vài phút
C. khoảng vài giờ một lần
D. khoảng vài ngày
Dẫn chứng: Halley's bell was an improvement in that its design allowed for an additional supply of fresh air that enabled a crew of divers to remain underwater for several hours.
=>Chọn C
According to paragraph 5, what part did the cables play in OSPREY’s design?
The word “overburden” in paragraph 1 is closest in meaning to_________
According to paragraph 3, which of the following is true about wave–power technologies?
What does the term 'international boycott' in paragraph 3 refer to?