题干

下列叙述正确的是                                   (     )

A:同温同压下,相同体积的气体,其分子数一定相等,原子数也一定相等

B:任何条件下,等物质的量的甲烷(CH4)和一氧化碳所含的原子数一定相等

C:同温同压下的二氧化碳气体和氮气,若体积相等,则质量一定相等

D:同温同压下,1L一氧化碳气体一定比1L氧气的质量小

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D

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    Businesses are finding more uses for Virtual Reality (VR) as the technology develops. VR is no longer only for gaming or enjoyment. An American company called Blue Goji is using VR to improve one's health by making exercise more fun.

    Blue Goji has offices in Austin, the capital of Texas. The company showed its cardiovascular (心血管的) workout machine, called the Infinity treadmill (跑步机), at the recent South by Southwest festival, an event held every year in Austin.

    A person using the treadmill wears a virtual reality headset when exercising. Before starting, the user tightens a belt to prevent falls. Then, the user plays a VR game while running on the machine. The game can transport the user into the virtual world, where he or she can be racing against virtual people.

    Recently, Leonardo Mattiazzi tested the Infinity treadmill. Mattiazzi said he had a strong feeling to actually get running and do something that pushed his limits. He said the experience was more interesting than running inside the gym without actually going anywhere.

    Constam said the active use of virtual reality helps solve a common problem while wearing a VR headset. She noted that a lot of VR experiences cause motion sickness because people are in motion during the game, but not moving in real life. But when the user is moving on the treadmill and in the game, the chances of motion sickness are reduced.

    However, users who tested the treadmill while wearing the VR headset each had a different experience. Constam said there generally is a learning curve for VR. The first time users feel lost, but "the more you do it, the more you get used to it," she said. Mark Sackler was a first time user. He said he felt a little sick at one point during the game. But he thought the experience was surprisingly realistic.

    After carefully studying the users' experiences, Blue Goji plans to make the treadmill available to the public in 2019.