SIS模型与考虑生死的SIS模型的求解过程完全不同。

A、在疾病传播期内，所考察地区的总人数N不变，既不考虑生死，也不考虑迁移

B、把人群N分为易感染者（Susceptible）和已感染者（Infective）两类

C、病人治愈后不会再成为可被感染的健康者

D、每天被治愈的病人数占病人总数的比例为常数

E、病人治愈后成为仍可被感染的健康者

A．Either of the books is popular with the students.

B．You can park on either side of the street.

C．I don"t like the red shirt and I don"t like the green one either.

D．You may either stay at home nor go there with us.

A．The United Negro College Funds is the oldest minority education support organization.

B．More than 54,000 students have graduated from United Negro College Fund member colleges since 1944.

C．Since its founding, the United Negro College Fund has raised more than $1.3 billion.

D．The United Negro College Funds is a combination of 39 private, historically black member colleges and universities.

A．None of the following statements is true.

B．Silicon Valley has great deposits of silicon.

C．London and Zurich have vast amounts of arable land.

D．Western Europe has always depended on services.

此题为判断题(对，错)。

A、.sisx/.sis

B、.apk

C、.cab

D、.ipa

B、1857

C、1867

D、1877