水的硬度是（） |水的碳酸盐硬度是（） |水的非碳酸盐硬度是（）
A.钠、镁等盐类的总量
B.钙、镁等离子的总量
C.钙、镁的硫酸盐和氯化物
D.钙、镁的重碳酸盐和碳酸盐
E.所有阳离子的总量
参考答案：B|D|C
解析：水的硬度是指溶于水中的钙镁离子的含量，分为碳酸盐硬度和非碳酸盐硬度。碳酸盐硬度是指钙镁的重碳酸盐和碳酸盐；非碳酸盐硬度是指钙、镁的硫酸盐和氯化物。
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| Can you really travel around the world for free? Li Jun, a 17-year-old girl from Shenzhen Foreign Language School, still can't __1__ her l0-day free training camp in the Alps in Switzerland last month was true ! But __2__ did she achieve this once-in-a-lifetime opportunity ? Last October, a piece of short world __3__ in a newspaper "Have a chance to see the world, for free", caught her eyes. When she asked her friends if the story was __4__, they laughed at her, for they thought she was day-dreaming. However, Li decided to apply (申请) on-line the following weekend. "Opportunity is everywhere. I'd like to keep my eyes open and catch the chance." she told herself. What happened next was tests on health, hobbies and awareness (意识) of environmental protection. She __5__ all of them very easily. On December 14, Li Jun surprised her friends with an invitation letter from the program, the Pangaea Young Explorer Selection Camp __6__ by South African explorer Mike Horn. __7__ January 11, Li left for Switzerland, with several newly bought ski-suits in her suitcase. Over the next week, she and 15 other teenagers from around the world __8__ exciting training and lessons. They took day-trips up the Alps to an altitude (纬度) of 3,200 meters, went sledging (滑雪橇) at night using modern equipment. They were also encouraged __9__ difficult journeys up mountains, down hills, and through forests. Because of her performance during the training, Li was chosen as one of the eight young __10__ to join Mike Horn in the South Island of New Zealand in May. She will write for the newspaper and share her fun experiences there with readers. | ||||
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