According to some scientists, this happens for two reasons.
根据一些科学家的说法，这种情况的发生有两个原因。
Now, some scientists are worried that such a famine could happen again, but on a much wider scale.
现在，一些科学家担心这样的饥荒可能会再次发生，但规模会大得多。
Although many lines of evidence indicate that birds evolved from ground-dwelling theropod dinosaurs, some scientists remain unconvinced.
尽管有许多证据表明鸟类是从陆生兽脚亚目恐龙进化而来的，但一些科学家仍然表示怀疑。
However, some scientists think although we can make robots move like people, it will be difficult to make them really think like a human.
然而，一些科学家认为，虽然我们可以让机器人像人一样行动，但却很难让它们真正地像人一样思考。
Therefore some scientists postulate that the Earth's earliest atmosphere, unlike that of today, was dominated by hydrogen, methane, and ammonia.
因此，一些科学家推断，地球早期的大气与现在的不一样，主要由氢、甲烷和氨构成。
Indeed, the human history has not been merely touched by global climate change, some scientists argue, it has in some instances been driven by it.
事实上，一些科学家认为，人类历史不仅仅受到全球气候变化的影响；在某些情况下，它还受到全球气候变化的推动。
However, in the late 1980s, some scientists were exploring Devil' s Hole, which is basically an extensive water-filled cave, far from the ocean, in Nevada2, in the western United States.
然而，在20世纪80年代后期，一些科学家在美国西部的内华达探索魔鬼洞，这基本上是一个广阔的充满水的洞穴，并且远离海洋。
This ability to reproduce is making some scientists worried.
这种再生产能力让一些科学家感到担忧。
Now, some scientists have come up with some different ideas.
现在，一些科学家提出了一些不同的想法。
10 years later, some scientists still didn't accept that there was life on Mars.
10年后，一些科学家仍然不接受火星上有生命的说法。
The test lasted for 21 days because some scientists believe that 21 days is long enough to help form a habit.
这项测试持续了21天，因为一些科学家认为21天足以帮助形成一种习惯。
But there are things about it that make some scientists uneasy.
但是，也有一些事情使科学家感到不安。
But some scientists in recent months have raised questions about the field.
但是有些科学家最近几个月中就此提出疑问。
After Schmidt's death in 1933, some scientists cast doubt on his Sargasso proposition.
1933年，施密特去世后，一些科学家对他的马尾藻命题发出了质疑。
And some scientists, especially, have wondered why we're sending humans to space at all.
甚至一些科学家质疑，为什么我们要把人送上太空。
That nonhumans are conscious remains controversial for some scientists, although their Numbers are dwindling.
对于一些科学家来说非人类拥有意识还是有争议的，尽管这些科学家的数量正逐步减少。
These occasional comet showers could be why the mass extinctions on Earth are so regular, some scientists believe.
一些科学家认为，这些偶然的彗星雨可能就是为什么地球上的大规模物种灭绝如此规律地发生的原因。
Neanderthals are believed to be modern humans' closest ancestor, and some scientists view both as the same species.
尼安·德塔人被认为是现代人最接近的远祖，有些科学家甚至把两者看做是同一个物种。
So perhaps the question to ask, say some scientists, is not how birds got their feathers, but how alligators lost theirs.
因此，有科学家表示，研究者需要探讨的问题并非是鸟类如何获得羽毛，而应该是鳄鱼如何丧失羽毛。
But still some scientists say those divers, and other thrill seekers are not necessarily to blame for the Titanic's current woes.
尽管这样，仍然有一些科学家声称潜水者和冒险家们并不一定要对泰塔尼克号目前的不幸负责。
Given that the body contains only 10 trillion cells, some scientists joke that the human-microbe hybrid is 10% human and 90% microbe.
鉴于人体只含有10万亿个细胞，一些科学家们开玩笑说，人类微生物混杂体其实是10%的人类和90%的微生物。
But as neural devices become more complicated - and go wireless - some scientists say the risks of "brain hacking" should be taken seriously.
但由于神经装置变得更加复杂——并且无线化——一些科学家说，得好好对待“人脑入侵”的风险了。
But some scientists have contemplated ways to change a planet's environment so that it can support life through a process known as terraforming.
不过，一些科学家考虑通过一些人为手段，改变行星环境使其适宜人类居住。
The idea of even testing such a system scares many people, and some scientists argue that climate-engineering research should remain theoretical.
只是测试这个系统就吓倒了许多人，一些科学家认为，气候工程研究应停留于理论层面。
It's not known how babies acquire the capacity to understand others' mental states, but some scientists have argued that conversation has a key role.
现在仍不清楚婴儿是如何具备探知他人思想能力的，但是有些科学家认为沟通起了关键作用。
It's not known how babies acquire the capacity to understand others' mental states, but some scientists have argued that conversation has a key role.
现在仍不清楚婴儿是如何具备探知他人思想能力的，但是有些科学家认为沟通起了关键作用。
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