题目原文：
The fossil record shows that members of the group of dinosaurs known as lambeosaurs had large bony crests on top of their heads The shape of the crests varied from species to species, but all lambeosaur crests contained extended hollow passages. No one really knows exactly what function the crests served, but scientists have offered several theories.
Sense of smell
One theory holds that the primary purpose of the crests was to improve the dinosaurs’ sense of smell. Examination of the fossils has suggested that the crests contained many blood vessels. The nose bones of modern animals with a highly developed sense of smell have a similar inner structure characterized by a high density of blood vessels. Thus, it is reasonable to conclude that the crests were primarily used to enhance the sense of smell.
Cooling
A second theory maintains (hat the crests served to prevent overheating by lowering lambeosaurs1 body temperature. The addition of a crest had the effect of increasing the surface area of the lambeosaur’s body, thereby allowing body heat to escape more rapidly. Other warm-climate dinosaurs, stegosaurs for example, also had bony crestlike plates on parts of their body that increased the body surface area. It has long been believed that the bony plates of stegosaurs were adaptations to improve cooling, so it seems likely that the crests of lambeosaurs served the same purpose.
Sound
A third possibility is that lambeosaurs used the crests to make sounds, perhaps for communication with other lambeosaurs It was definitely possible to make low sounds by forcing air through the crests. This theory is supported by a finding suggesting that lambeosaurs had a good sense of hearing paleontologists recently discovered remains of a lambeosaur that had a highly developed inner ear. A good sense of hearing would be necessary for animals communicating by sound
题目音频：
学术写作：
学术写作
Doctor Achebe:
As we have been discussing in class, deciding where to donate money is an important consideration when supporting charitable causes. Some prefer local charities where the impact may be more visible, while others favor international ones tackling issues on a broader scale. With this in mind, when donating money to charity, what factors do you take into account when choosing between local and international organizations?
Andrew:
I prefer to give to local charities rather than international ones. Local organizations where I live allow me to witness firsthand the impact my contributions make. The visible difference – even a small amount – motivates me to keep supporting groups creating visible change close to home.
Claire:
I believe supporting international charities is most impactful. Though local charities do good work, global issues like climate change and poverty affect millions more people. International groups have the scale and resources to drive systematic change on these pressing problems in ways smaller organizations simply can’t. Donating to major international charities can thus create widespread, meaningful impact.
