2. We learned about fetal surgery’s potential to change lives.
4. 2. American shale.By the end of 2014, the U.S. was producing more than 9 million barrels of oil per day, an 80 percent increase from 2007. That output went a long way to creating a glut of oil, which helped send oil prices to the dumps in 2014. Having collectively shot themselves in the foot, the big question is how affected U.S. drillers will be by sub-$60 WTI. Rig counts continue to fall, spending is being slashed, but output has so far been stable. Whether the industry can maintain output given today’s prices or production begins to fall will have an enormous impact on international supplies, and as a result, prices.
5. found（v 建立；使有根据）作为词根表示：底部
6. Last year was especially striking because global heat records were broken or tied in every month except January and April, researchers said.