New findings in scientific areas can examine and challenge previous assumptions. A recent finding concerning the meerkat, a burrow-dwelling animal in the African grasslands, has cast doubt upon the conventional ideas of altruism, the type of behavior in which an animal sacrifices its own interests for the benefit of another.

　　Meerkats were previously thought to be a typical altruistic animal. When the other meerkats feed, there is usually one meerkat watching out for predators. The sentinel meerkat gains nothing, it seems, for it can neither eat nor escape quickly and successfully after raising an alarm.

　　However, in the new findings, it's shown that the sentinel meerkat has already eaten food before standing guard, thus contradicting the thought that it has an empty belly while on the lookout. In addition to this, the sentinel is the first to see a predator, so it is the first to escape. It is also placed nearest a burrow, making it relatively easier to flee. Moreover, its alarm calls may cause the group either to gather or to spread rapidly, which may attract the predator's attention, providing the sentinel a better chance to escape.

　　The same is with supposed human altruistic behavior. Organ donation to strangers may be considered an unselfish act, which provides little reward to the donator. However, by donating his organ, the donator may most probably receive praise and appreciation from others. Isn't this non-material reward, which increases one's self worth, satisfactory to anyone?

　　第二篇作文：

　　Do you agree or disagree with the following statement?

　　Good teachers are more important to a child's development than good parents.

　　Parents and teachers are both important people to a child. Some people say, "Good teachers are more important to a child's development than good parents." However, I do not agree with this statement.