文章是这样的:
When the elements known at the time when ordered by increasing atomic mass, it was found that successive elements belonged to different chemical groups and that the order of the groups in this sequence was fixed and repeated itself at regular intervals.
题目:
According to paragraph1, what pattern did scientists notice when the known elements were written in order of increasing atmoic mass?
1.The elements of the group of alkali metals were the first elements in the order of increasing atomic mass.
2.Repetition of the same atomic messes for elements in different groups appeared.
3.Elements with similar chemical properties appeared in the listing at regular intervals.
4.Elements were chemically most similar to those just before and after them in the order.