关于x的方程mx2+2（m+1）x+m=0有两实根，则m的取值范围是______

某水域中鱼类大面积死亡，调查得到的结果如下：

①居民向该水域排放含磷洗涤剂；②有大量运输船在水里航行；③水域中有适量的水草；④上游化工厂向水域排放废水；⑤鱼类把水中的氧气消耗光了；⑥鱼呼吸时产生的二氧化碳溶解于水中；⑦水域沿岸的农民种植作物时施用了过量化肥农药。你认为可能的原因有                                            

A．①④⑦

B．②③⑥

C．④⑤⑥

D．③⑥⑦

SF6断路器解体检修时，灭弧室内吸附剂应进行烘燥再生处理。

采用中间电位作业时，屏蔽服所起的主要作用是（）。

A.屏蔽高压电场、分流高频电流；

B.屏蔽电场；

C.分流静电感应电击电流；

D.与带电部分隔离。

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.

Notes: childhood amnesia 儿童失忆症。

14（）

A.instincts

B.feelings

C.sensations

D.experiences

整流器ZXD1800 75A输入电压允许变化范围是（）。

A.80VAC-300VAC

B.100VAC-300VAC

C.120VAC-300VAC

D.154VAC-286VAC