The more people who have the virus, the more virus particles there are for that one, fatal mutation to appear in.
因为如果有越多人感染到病毒，就有越多病毒颗粒可以酝酿出一种致命的突变病毒品种。
For example, it is hard to say whether an ART baby has died because of the ART technology or because one of its parents had a mutation that mutually contributed to subpar fertility and infant death.
Analyzes the factors that influence the stretching changing in the hoisting process and put forward a method that adopting S-curve could reduce the stretching mutation.
