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The flu is believed _______ by viruses that like to reproduce in the cells inside the human nose and throat.

A．causing	B．being caused
C．to be caused	D．be have caused

It’s very dangerous to _______ these viruses without any protection.

A．be exposed to

B．expose to

C．expose

D．be exposing to

The flu is believed ________ by viruses that like to reproduce in the cell inside the human nose and throat.

A．causing	B．being caused
C．to be caused	D．to have caused

[ ]

“If we don’t often wash our hands, we can pick up viruses（病毒）form many places and make ourselves ill,” a man from CDC says. Doctors always say every time when you touch your eyes, nose or mouth, you may be ill. In fact, one of the common（平常的） ways of catching a cold is by rubbing（擦拭）their noses or their eyes when there are viruses on their hands. If you don’t often wash your hands, especially when you’re sick, you may spread the viruses to others. You should wash your hands in these situations:
1. After using the washroom
2. After rubbing your nose or coughing.
3. Before eating or making food.
4. After touching animals.
5. After visiting a sick man.
6. When your hands are dirty.
There’re right ways to wash your hands. Follow these things to keep your hands clean:
1. Use warm water (not cold or hot).
2. Wash for 15 seconds.
3. Wash well under warm running water and dry them with a clean towel.
阅读短文，填表格。
Information Card

A way to protect against the spread of illness	1
Situations in which you must wash your hands	After using the 2 Before making 3 After visiting the 4 people
A correct way to wash your hands	Use 5 running water
Time needed to wash your hands	6

The flu is believed ______ by viruses that like to reproduce in the cells inside the human nose and throat.

A．to be caused

B．to have caused

C．being caused

D．causing