Scientists have yet to pinpoint the mechanisms involved but have come up with several （ ）explanations.
举一反三
- and scientists have yet to develop a magic ________ that keeps the kilos off permanently.?
- We ________ on it for several hours but we have not yet reached any conclusion.
- With the population explosion, scientists will have to __ new methods of increasing the world’s food supply. A: lead to B: carry on C: come up with D: stick to
- 4. We ________ on it for several hours but we have not yet reached any conclusion. A: A. work B: B. are working C: C. have been working D: D. have been worked
- Chinese and Russian scientists have reported that in places ( ) stress is building up, the radon levels of the water build up too.