下列句子中没有语病且句意明确的一句是（    ）

我国北疆边防哨兵在严寒的冬季会穿上一种电热靴．如图为电热靴内加热电路的示意图，电源两端电压保持不变，S₂为三档旋钮开关（金属片M可分别拨至a、b、c处），电阻丝R₁、R₂规格相同且阻值不变，b为电阻丝R₁的中点．闭合开关S₁，这只电热靴的低温档、中温档、高温档应分别将金属片M拨至（　　）

阅读短文，判断正误。
Dear Joe,
    How are you? My sister and I are having our holiday. Yesterday we went to the library. We got there by bus. We read storybooks and had lunch there. The food was delicious. It was cheap, too. We went shopping in the afternoon. I bought a pair of shoes. I was very tired. We are planning to learn skating and do many other things during the holiday. We are sure we'll have a good time.
    How about your holiday? Please write to me soon.
Miss you.
Alice

2016年被许多人称为VR（虚拟现实）元年。VR设备用户量大面积上升，2016年大概会销售2000 万台VR设备。这种情况下，越来越多资本看好VR内容（影视、游戏等）市场，大量投资蜂拥而至。大量投进入VR内容领域的依据是（  ）

①作为互补商品，VR设备销量增加会带动内容需求增多

②作为消费升级形成的新需求，VR内容消费将决定VR产业的发展

③作为享受资料，VR内容消费将完全取代发展资料的消费

④作为新的消费热点，VR内容生产能为投资者带来丰厚利润

某Flash文档的部分编辑界面如图所示，以下说法正确的是（   ）