免疫系统就像一把双刃剑;它可以对抗癌症,但也需要被控制。
越南人民深深热爱独立、自由与和平。但在面对美国的侵略时,他们团结一致奋起反抗。
冒险本身就是值得的。
"Reading is the most important skill a child can learn."
The function of mental processes is to mediate between the needs of the organism and the demands of the environment.