《The Emperor of All Maladies: A

When cells divide, they need to make copies of DNA--the chemical that carries all the genetic information in a cell. Folic acid is a crucial building block for DNA and is thus vital for cell division. Since blood cells are produced by arguably the most fearsome rate of cell division in the human body--more than 300 billion cells a day--the genesis of blood is particularly dependent on folic acid. In its absence the production of new blood cells in the bone marrow halts. Millions of half-matured cells spew out, piling up like half-finished goods bottlenecked in an assembly line.

当细胞分裂时，它们需要复制 DNA —— 细胞中一种携带所有遗传信息的化学物质。而叶酸是 DNA 的关键组成部分，因此叶酸对细胞分裂是必不可少的。由于血细胞可以说是人体中最令人恐惧的细胞分裂速率——每天超过3000亿个细胞——血液的生成特别依赖于叶酸。如果没有它，骨髓中的新血细胞就会停止。 数以百万计的半成熟细胞喷涌而出，像半成品一样堆积在工厂的流水线上。

• crucial /ˈkruːʃl/ adj. extremely important, because it will affect other things 至关重要的；关键性的
• vital /ˈvaɪtl/ adj. necessary or essential in order for sth to succeed or exist 必不可少的；对…极重要的
• bottleneck /ˈbɑːtlnek/ n. 瓶颈，阻碍，障碍