【听力原文】
Thank you. It's great to see so many of you interested in this series on "Survival in the Outer Space". [19]Tonight I'm going to talk about one of the most basic aspects of survival: the space suit. When most of you
imagine astronaut, that's probably the first thing that comes to mind, right? Well, without space suit it will not be possible for us to survive in space. For example, [20] outer space is a vacuum. There's no gravity or air pressure. Without protection, a body would explode. What's more, we cook in the sun or freeze in the shade with temperatures ranging from a toasty 300 degrees above to a cool 300 degrees below zero Fahrenheit. The space suit that NASA has developed is truly a marvel. [21] This photo enlargement here is a life size image of an actual space suit worn by astronauts on the last space shuttle mission. This part is the torso. It is made of seven extremely durable layers. This thick insulation protects against temperature extremes and radiation. Next is what they call a bladder of oxygen. That's an inflatable sack filled with oxygen to simulate atmosphere pressure. This bladder presses against the body with the same force as the earth atmosphere at sea level. The innermost layers provide liquid cooling and ventilation. Despite all the layers the suit is flexible, allowing free movement, so we can work. Another really sophisticated part of the space suit is the helmet. I brought one along to show you.
What's the speaker's main purpose?
【解题思路】四项均为不定式短语，均提及space。由于该题处于第一题，且选项核．心动词分别为show、gain、describe、inform，因此本题很有可能是问讲话者的目的，即短文的主旨。
【解析】短文开头处提到： “欢迎收看《外太空生存》系列节目，今晚我们来谈一谈涉及太空生存的最基本因素中的其中一个：宇航服。”随后讲话者简要介绍了宇航服的功能以及其各个部分。故选D。