求教两道prep题，谢谢

1。Officials at the United States Mint believe that the Sacagawea dollar coin will be used as a substitute for four quarters more for the dollor bill because it weighs only 8.1 gram,far less than four fquarters, which weigh 5.67grams each.

我就是想问一下，这道题比较的双方到底是什么，有点搞不清楚，这句话是正确的。

2。Scientists say that each of the photographs taken of the Ares Vallis plain by the Mars Pathfineder indicates the overwhelming extent of the flooding on the planet billions of years ago and the degree to which rocks were scattered by its force.

这句话也是正确的，我想问不是有 each of +复数＋谓语动词用复数。这样的说法吗？？这里为什么用indicates啊？？

1>意思是那个Sacagawea dollar coin更多得被用来代替4个quarter，而不是dollar bill（指1美元的bill），因为它的份量比4个quarter还要小

2>有each of的用法

举例： We each have a book.    Each of us has a book.