1. Essentially, a theory is an abstract, symbolic representation of what is conceived to be reality.
本质上，理论是对认识了的现实的抽象化和符号化的概括。 2. Long before children are able to speak or understand a language, they communicate through facial expressions and by making noises. 远在孩子还不能够说话和听懂话的时候，他们通过做面部表情和发出噪音来和人沟通。
3.Thanks to modern irrigation, crops now grow abundantly in areas where once nothing but cacti and sagebrush could live.
感谢现代灌溉技术，玉米在以前仙人掌和山艾树才能够存活的地方也可以大量生长。
