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阅读图文材料,完成下列要求。

2016年1月21日~23日,一场“霸王级”寒潮侵袭了我国大部分地区,致使我国部分地区的越冬农作物遭受冻害,华北地区的大量冬小麦受损严重。下面为华北地区某冬小麦农田和冬小麦受损景观图。

说出本次寒潮对冬小麦造成的主要危害,并列举冬小麦防治冻害可采取的工程措施。

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答案(点此获取答案解析)

危害:造成冬小麦枯萎或死亡(冬小麦减产绝产)。措施:寒潮来临前浇水,改善土壤墒情;压实保墒;释放烟雾,增强大气的保温效应;用麦草或塑料薄膜等覆盖(增施草木灰);寒潮过后及时浇水(酌情追肥,喷施药剂等)。

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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.