题目内容：

    Coronaviruses(冠状病毒) are a large group of viruses. They consist of a core of genetic material(遗传物质) surrounded by an envelope with protein spikes(蛋白棘突). This gives it the appearance of a crown. Crown in Latin is called “corona” and that’s how these viruses get their name. In this text, we’ll take a quick look at what’s currently known about the virus.

Covid-2019

The 2019 Novel Coronavirus, first reported December in Wuhan, central China’s Hubei Province, has quickly spread across the country and around the world. It initially occurred in a group of people with pneumonia(肺炎) who’d been associated with a seafood and live animal market in the city of Wuhan.

Intermediate hosts: The Covid-2019 may originate in bats, a team led by renowned Chinese virologist Shi Zhengli said earlier, while the intermediary host remains unknown.

Incubation period(潜伏期): usually 1-14 days.

Infection: Virus may spread before symptoms show.

SARS-CoV

The Severe Acute Respiratory Syndrome (SARS) coronavirus was first identified in China in 2003 .

Intermediate hosts: Bats are the original host. Civet cats serve as an important intermediary that carries virus from the winged mammal to humans.

Incubation period: 2-7 days.

Infection: Virus spread after symptoms show.

MERS-CoV

The Middle East Respiratory Syndrome (MERS中东呼吸综合征) coronavirus was first identified in Saudi Arabia in 2012.

Intermediate hosts: MERS-CoV was travelled from dromedary camel to humans.

Incubation period: 2-14 days.

Infection: Virus may spread before symptoms show.

1.What might be the intermediate hosts of the Covid-2019?

A.Bats. B.Mosquitoes C.Camel. D.Unknown yet.

2.Which kind of coronaviruses spreads after symptoms appear?

A.SARS-CoV. B.MERS-CoV.

C.The Covid-2019. D.All Coronaviruses.

3.What can we learn about coronaviruses ?

A.Bats are to blame for the outbreak of all the three coronaviruses.

B.The Covid-2019, SARS-CoV and MERS-CoV are all listed as coronaviruses.

C.Mers-Cov were first identified in China.

D.SARS-Cov has a longer incubation period than Mers-cov.