This turbidity is caused by material present in the original black tea.

这种浑浊是由存在于原料红茶中的物质所引起的。

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Or a radioactive substance may be disintegrating at a known rate and we may be required to determine the amount of material present after a given time.

又如，某种放射性物质可能正在以已知的速度进行衰变，需要我们确定在给定的时间后遗留物质的总量。

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Dendritic cells in the germinal center may endocytose such antigenic material and present it to T cells, activating them.

生发中心的树突状细胞可以内吞这种抗原物质并将其呈递给 T 细胞，从而激活它们。

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First tests of the bone fragment showed that human genetic material, human DNA,was present.

VOA: special.2011.03.15

That means if there were organic material present there, it could have been preserved.

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Although the father's genetic material is present in the embryo and on the surface of the placenta, the mother's body does not reject it.

BBC: Immune treatment 'cuts IVF failures'

The IAEA said that before the war it inspected the Al Qaqaa facility multiple times and verified that the material was present in January 2003.

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