物物交换

Many phytoplankton and autotroph absorb the DIN of the bottom water that decrease content of DIN in bottom water and change the fluxes of the DIN. And the activity of those phytoplankton and autotroph can even change the direction of DINS fluxes.

在有光的条件下，浮游藻类和一些光自养生物对沉积物水界面溶解态的营养盐的直接吸收，从而减少了上覆水中可与沉积物可交换的营养盐的含量；浮游植物的活动甚至有可能改变无机氮在沉积物水界面的扩散方向。

At that time, much of the trade was conducted on a barter basis.

在当时，许多贸易都是在物物交换的基础上进行的。

To make an exchange of one thing for another.

交换：用一物与另一物进行交换

This theory is methodology that differentiate with the commodity exchange and labour exchange and resource collocation, and has the sustainable, quantifiable, and economical, profitable and valued-added characteristics.

具有不同于商品交换、物物交换及资源配置，具有可持续性、可量化性、节约性、增值获利等特性，是一种方法论。

The unique geographic position of shelf and marginal sea causes the material supply of seafloor sediments plenteous and the material sources of them diverse. As terrigenous materials being input into the sea continually and a great deal of authigenous minerals coming into being, the sediments can be used to study the change of sea level and the meterail and energy exchange between the sea and the land.

陆架和边缘海独特的地理位置决定了海底沉积物物源的充足与多样性，陆源物质源源不断地通过河流输入到海洋中，同时大量的自生矿物在海洋中生成，因此研究陆架和边缘海海底沉积物，可以为研究海平面变化、海陆之间物质和能量的交换等作用提供信息。

Of, relating to, or being something based on bartering

以物易物的，和物物交换有关的

At first, bartering took place as an exchange between two people.

最初的物物交换只是作为一种交换形式在两个人之间发生的。

At first, bartering took place as an exchange between two people.

过去，最早的&物物交换&是发生在2个人之间的一种交换。

Previously, anthropologists have already done lots of relevant researches about the exchange and the market, but limited systematic research on barter in market economy.

许多人类学家对交换和市场做了大量的研究，但是关于市场经济条件下的物物交换方面的系统研究则较少。

In a barter economy it would be necessary to determine how many plates were worth one hundred weight of cotton, or how many pens should be exchanged for a ton of coal, which would be a difficult and time-consuming task.

根据原文的上下文，我们可猜测出barter economy就是&物物交换经济&，由此可知正确答案为C：货物被交换，而不是用货币。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷