单选题 下列有关实验操作的叙述,不正确的是

A、 把玻璃导管插入胶皮管时,先要把玻璃导管一端用水润湿
B、 洗过的试管,只要试管内壁看不到杂物就表明已洗涤干净
C、 用量筒量取液体时,视线与量筒内液体的凹液面的最低处保持水平再读数
D、 实验剩余的药品,不能放回原试剂瓶
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相关试题

单选题 What is the main use of chlorine in water treatment?

A、to remove suspended solids
B、to adjust the pH value
C、to disinfect the water
D、to soften the water

单选题 Which of the following reactions involves the formation of chlorine?

A、the reaction between hydrochloric acid and potassium permanganate
B、the reaction between sodium chloride and sulfuric acid
C、the reaction between calcium carbonate and hydrochloric acid
D、the reaction between zinc and hydrochloric acid

单选题 Chlorine is produced industrially by the electrolysis of a solution of what?

A、sodium chloride
B、sodium hydroxide
C、sodium carbonate
D、sodium sulfate

单选题 Which of the following is not a property of chlorine?

A、it is a green - yellow gas
B、it is soluble in water
C、it has a sweet smell
D、it is a strong oxidizing agent

单选题 Chlorine reacts with water to form which of the following?

A、hydrochloric acid only
B、hypochlorous acid only
C、hydrochloric acid and hypochlorous acid
D、chlorine gas and water

单选题 If you are a diet - cola drinker, you might be surprised to learn that diet - cola actually has calories (卡路里).

A、如果你是一个常喝健怡可乐的人,你可能会惊讶地发现,健怡可乐实际上是有卡路里的.
B、如果你正在节食并喝可乐,你可能会惊讶地发现,健怡可乐实际上是有卡路里的.
C、如果你是一个常喝健怡可乐的人,你可能会感到惊讶去学习健怡可乐实际上是有卡路里的.
D、如果你正在节食并喝可乐,你可能会感到惊讶去学习健怡可乐实际上是有卡路里的.

单选题 If you're careful to buy packaged foods labeled "low - fat" or "non - fat", you might not be aware that many of them contain large amounts of carbohydrates (碳水化合物).

A、如果你小心翼翼地购买标有"低脂"或"无脂"的包装食品,你可能没有意识到其中许多含有大量的碳水化合物.
B、如果你小心地去买标有"低脂"或"无脂"的打包食物,你可能没有意识到其中许多含有大量的碳水化合物.
C、如果你小心翼翼地购买标有"低脂"或"无脂"的包装食品,你可能不明白其中许多包含大量的碳水化合物.
D、如果你小心地去买标有"低脂"或"无脂"的打包食物,你可能不明白其中许多包含大量的碳水化合物.

单选题 In fact, many so - called "diet" foods are filled with carbohydrates and other ingredients that can cause weight gain.

A、事实上,许多所谓的"节食"食品充满了碳水化合物和其他会导致体重增加的成分.
B、实际上,很多所谓的"节食"食物充满了碳水化合物和其他能引起体重增加的元素.
C、事实上,许多所谓的"节食"食品充满了碳水化合物和其他能引起体重增加的元素.
D、实际上,很多所谓的"节食"食物充满了碳水化合物和其他会导致体重增加的成分.