A survey was carried out on the death rate of those who were infected by Ebola Virus, __________were frightening.
| A．of that results | B．of which results |
| C．the results of that | D．the results of which |
Not recognizing me at first, __________.
| A．he closed the door | B．the door was closed |
| C．the door was close | D．I closed the door |
She was always _____ , even when things were at their worst.
| A．attractive | B．optimistic | C．pessimistic | D．frightened |
This also keeps the air，soil，water crops________ chemicals.
| A．out of | B．out from | C．free of | D．rid of |
____polite to others and you can get friendship in turn.
| A．Be | B．To be | C．Being | D．/ |
There are many tall old trees____ in and around our school.
| A．stood | B．to stand | C．standing | D．being standing |