Drone safety is not an option, but a baseline.
英国女王伊丽莎白二世来华访问时想见他，他说
The future of energy is low-carbon, but oil and gas will remain part of the mix for decades to come.
能源的未来是低碳的，但石油和天然气在未来几十年仍将是能源结构的一部分。
The true measure of our success in grain production lies not in the yield alone, but in how we balance productivity with environmental stewardship.
The goal of mathematics is to understand the structures that underlie the phenomena we observe.