搜题请搜索小程序“爱下问搜题”
问题 选择题

DNA上有许许多多控制生物性状的基本遗传单位，它就是

A．基因

B．水

C．无机盐

D．脂肪

答案

答案：A

DNA可以分成许多小段，其中每一份就称为一个基因，所以基因是DNA的功能单位和结构单位，是有遗传效应的DNA片段，基因控制性状．而水、无机盐和脂肪是人体所需的食物中的营养物质，不符合题意．故本题选A。

问答题

搜查
查看答案
单项选择题

What’s your earliest childhood memory Can you remember learning to walk Or talk The first time you heard thunder or watched a television program Adults seldom (1) events much earlier than the year or so before entering school, (2) children younger than three or four (3) retain any specific, personal experiences.

A variety of explanations have been (4) by psychologists for this "childhood amnesia". One argues that the hippo-campus; the region of the brain which is (5) for forming memories, does not mature until about the age of two. But the most popular theory (6) that, since adults don’t think like children, they cannot (7) childhood memories. Adults think in words, and their life memories are like stories or (8) one event follows (9) as in a novel or film. But when they search through their mental (10) for early childhood memories to add to this verbal life story, they don’t find any that fit the (11) . It’s like trying to find a Chinese word in an English dictionary.

Now psychologist Annette Simms of the New York State University offers a new (12) for childhood amnesia. She argues that there simply aren’t any early childhood memories to (13) . According to Dr. Simms, children need to learn to use someone else’s spoken description of their personal (14) in order to turn their own short-term, quickly forgotten (15) of them into long-term memories. In other (16) , children have to talk about their experiences and hear others talk about (17) --Mother talking about the afternoon (18) looking for seashells at the beach or Dad asking them about their day at Oceanz Park. Without this (19) reinforcement, says Dr. Simms, children cannot form (20) memories of their personal experiences.

Notes: childhood amnesia 儿童失忆症。

（12）（）

A.emphasis

B.assertion

C.explanation

D.assumption
查看答案