Once harm ______ to the environment, it takes years to have the system recovered.
| A．does | B．is done | C．will be done | D．be done |
The doctor kept telling him that he mustn’t smoke, but ________ didn’t help.
| A．he | B．which |
| C．it | D．they |
Don’t leave your keys in the car. Someone might steal ________ 。
| A．one | B．that |
| C．this | D．it |
Computers must be of great use to ________ doing the scientific research.
| A．these | B．whoever |
| C．those | D．whomever |
The cruelty of the Germans towards the Jews and ________ of the Japanese towards their prisoners, filled ________ with horror.
| A．those; someone | B．that; everyone |
| C．it; no one | D．this; anyone |
At the shop, they wanted to show me all the dresses, but I was interested only in ________ in the window.
| A．this | B．that |
| C．it | D．the one |