问题
单项选择题
生产烟花爆竹产品时,当车间相对湿度低于多少时,不得加工制药和装、筑药()%。
A、30
B、40
C、50
答案
参考答案:B
生产烟花爆竹产品时,当车间相对湿度低于多少时,不得加工制药和装、筑药()%。
A、30
B、40
C、50
参考答案:B
The Peppered Moth, a kind of insect(昆虫), is found in England. It is light brown in colour and likes to settle(栖息) on trees which are also light brown. This makes the moth difficult to be seen and birds are less likely to notice and eat it. But with the development of industry(工业) , smoke from factories began to reach the trees where the moth settled. It made the trees blacker. Then something very strange took place: in industrial areas, the Peppered Moth began to change colour. It became darker as well. Though the change took several years, some scientists soon notice that newly-born moths were a little darker than usual. A scientist with the name Kettlewell decided to make a careful study of this phenomenon(现象). He marked some of the light moths and some of the darker ones, and set them free in the woods near Bermingham, an industrial city. Later, he recaptured(重新捕获) as many as the marked moths as possible. The results were as follows.
Can you imagine what would happen to the Peppered Moth as the air became cleaner again? 小题1:The Peppered Moth began to change its colour in industrial areas because .
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