粗盐水过滤后仍含有可溶性的CaCl₂、MgCl₂、Na₂SO₄等杂质，通过如下几个实验步骤可以除去这些杂质． ①加入稍过量的Na₂CO₃溶液；②加入稍过量的NaOH溶液；③加入稍过量的BaCl₂溶液；④滴入稀盐酸至无气泡产生；⑤过滤．正确的操作顺序是（　　）

    A man feared his wife wasn't hearing as well as she used to and he thought she might need some hearing aid (助听). Not quite sure how to 1 her, he called the family doctor to discuss the problem. The doctor toldhim there was a simple test the husband could do to give the doctor a better 2of her hearing loss.

    "Here's what you do," said the doctor. "Stand about 40 feet away from her, and in a 3 conversational speaking tone (音调) see if she hears you. If not, go to 30 feet, then 20 feet, and so on4 you get a reply."

    That evening, the wife was in the 5, and he was in the yard. He said to himself,"I'm about 40 feet away, and let me see what will happen." Then in a usual tone he asked,"Honey, what's for dinner?"

    No 6 .

    So the husband moved closer to the kitchen, about 30 feet from his wife and asked,"Honey, what's for dinner?"

    7no reply.

    Next he moved into the dining room where he was about 20 feet from his wife and 8, "Honey, what's for dinner?"

    Again he got no reply. He walked up to the kitchen door, about 10 feet away. "Honey,what's for dinner?" Again there was no reply.

    So he 9  right up behind her. "Honey, what's for dinner?"

"Chicken! James, for the 10 time I've said that."

你能根据所学的知识把下列生物分类吗？请尝试回答以下问题：

①虾 ②鳖 ③乌贼 ④河蚌 ⑤海蜇 ⑥鲸  ⑦鲨

填空。