What are your favorite smells? Plucking some examples out of thin air, they might include the aroma of freshly brewed coffee, the scent of recently cut grass, or the smell of barbecuing food. In short, they’re probably smells that you can __1__ on a regular basis here on planet Earth. But have you ever stopped to consider what the rest of the universe smells like?
Due to the chemicals present in their atmospheres, some of our __2__ planets actually do not smell like much at all. Mercury is rich in hydrogen, sodium, potassium, and helium—elements which don’t have specific smells. Saturn and Neptune are mainly composed of hydrogen and helium and are thus similarly __3__. In fact, around 99 percent of the known universe __4__ these two elements, meaning it’s unlikely to make it onto your favorite smells list.
It’s highly doubtful that the __5__ one percent will make it on there, either. That’s because other famous planets in our solar system—namely, Venus, Mars, Jupiter, and Uranus—stink ofrotten eggs. This is due to the __6__ of high concentrations of chemicals like sulfur, ammonia, and hydrogen sulfide.
However, there are pockets of __7__ aromas out there in deep space. Arrokoth, an asteroid-like object in the Kuiper Belt, is said to smell like a __8__ of alcohol and almonds. Sagittarius B2, a cloud of dust and gas light years away from us, smells ofraspberries and rum, thanks to the chemical ethyl formate.
It’s reasonable to ask how we know all of this, and the answer involves spectroscopy. This is the study of how matter __9__ or absorbs light. Basically, scientists analyze light from objects in space and __10__ it to what we know about chemicals on Earth. This way, they can work out what the objects in space are made up of. Now you know what to expect if you ever visit the outer reaches of our solar system.
(A) pleasant (B) remaining (C) compare (D) odorless (E) sends out (F) consists of (G) combination (H) encounter (I) presence (J) neighboring
答案： 1. H 2. J 3. D 4. F 5. B 6. I 7. A 8. G 9. E 10.C
