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."

科技小组计划选一块600平方米的实验田．（从左往右填表）

____ 

仔细观察这个表格，你发现了什么？

我发现____ ．

在洋葱根尖细胞中，组成核酸的碱基、五碳糖、核苷酸各有几种（）

 如图所示的电路，开关闭合后，电压表的示数是1.5V，的示数是4.5V，则电源电压是（　　）