她的大儿子，26岁的小大卫确实找了一份好工作。
城市居民的碳足迹其实是相对小的，这就是大卫·多德曼在《环境和城市化》的四月刊号中提出的发现。
The carbon footprint of urban dwellers is relatively light, says a report by David Dodman in the April issue of Environment and Urbanisation.
更秘密的太空研究则设想，比方说可以发射小卫星充当“守护天使”，来侦测针对大卫星的可能攻击。
More esoteric space research has ideas such as sending small satellites to act as “guardian angels”, detecting possible attacks against the big birds.
应用推荐