某小组在调查池塘中的生物时，用光学显微镜不能观察到的是（ ）
A．
草履虫
B．
艾滋病病毒
C．
衣藻
D．
眼虫
答案：B
由于雪橇和捆绑技术的提高，在滑雪场坡道上受伤的事故已明显下降——从 1960年的0.9%下降到1990年的0.3%。而其他与滑雪相关的事故，即发生在滑雪场而不在坡道的事故，却从1960年的10%上升到1990年的25%。这些事故，如绊倒等，随着每个滑雪者饮酒量的上升而上升。 如果以上论述为真，以下哪一项不可能假( )
A．1990年发生在坡道上的事故数量少于1960年发生在坡道上的事故数量
B．1990年发生在滑雪场而不在坡道的事故数量多于1960年发生的同类事故数量
C．如果雪橇和捆绑技术继续提高，与滑雪相关的事故将继续减少
D．1990年发生在坡道上的事故占全部与滑雪相关事故的比例小于1960年的比例
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 Ocean Park. Without this (19) reinforcement, says Dr. Simms, children cannot form (20) memories of their personal experiences.
6（）
A.declines
B.assesses
C.estimates
D.maintains
