While the clonal selection principle is responsible for generating the memory cell population, the immune network theory prevents the population size from increasing quickly.
克隆选择用来产生抗原的记忆细胞群体，免疫网络理论则用来抑制该群体规模的快速增长。
The population on Earth is still increasing quickly.
地球上的人口仍然在快速增长。
The world's population is increasing very quickly.
世界人口正在快速增长着。
The world's population is increasing very quickly.
世界人口正在快速增长着。
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