Dolphins once were hunted for money because______.
A: they are rare and precious animals
B: valuable oil can be obtained form their head
C: they can produce oil for lubrication
D: they are able to utter sounds worth study
A: they are rare and precious animals
B: valuable oil can be obtained form their head
C: they can produce oil for lubrication
D: they are able to utter sounds worth study
举一反三
- Advanced technologies can do all of the following EXCEPT that ______. A: they can find oil deeper in the ground B: they can increase mining efficiency C: they can cultivate microorganisms that produce oil D: they can delay peak oil production
- Rare animals are still hunted, ______ we can now imitate their skins with other products. A: when B: ever since C: so that D: even though
- Scientists once thought that men are different from animals because ________. A: they can think and learn B: they can make tools C: they can speak
- What can we learn from the first paragraph（） A: A dolphin is a special kind of fish. B: Dolphins can"t swim very quickly. C: Dolphins can live only in the sea. D: Dolphins produce their babies on land.
- In one day, Sue can change the oil on 20 cars or change the tires on 20 cars. In one day, Fred can change the oil on 20 cars or change the tires on 10 cars. Sue and Fred can gain from trade if Sue changes the ( ) and Fred changes the ( ). A: tires; oil B: oil; oil C: oil; tires D: tires; tires