钢铁分析中锰的测定-过硫酸铵容量法，在方法里加入氯化钠的作用不是什么？写出反应方程式？

The first people to inhabit North America came from Asia. Scientists had hypothesized that these people traveled across a now-submerged landmass that connected the two continents until 14,000 years ago, depending for food only on the land animals they hunted as they traveled. Recent discoveries have led to the new hypothesis that the first people came by boat along the southern shore of the landmass, eating fish and sea mammals.
Which of the following, if true, most ply supports the new hypothesis by casting doubt on the earlier hypothesis

A．The landmass connecting North America and Asia extended very far to the north.

B．In Europe, maritime cultures primarily dependent on the sea for food developed no earlier than 10,000 years ago.

C．People living in Asia at the time the two continents were connected hunted land animals for food.

D．The landmass was so bitterly cold that its vegetation would have been too sparse to support land animals.

E．(E) Sophisticated and mature North American and Asian cultures that display great similarities to each other existed as far back as 8,000 years ago.