This new kind of chemicals will help keep the air, soil and water________ from pollution.
| A．free | B．empty | C．loose | D．short |
Tony ______ his homework this morning before he went to school.
| A．has done | B．did | C．has done | D．will do |
He was about to tell me the secret _______ someone patted him on the shoulder.
| A．as | B．when | C．while | D．then |
E-mail, as well as telephones, _____ an important part in daily communication.
| A．is playing | B．have played | C．are playing | D．play |
Hiking is ______ great fun. You will get close to ______ nature and take exercise at the same time.
| A．a; the | B．a; ／ | C．／; the | D．／; ／ |
Police have not_______ the possibility ______ the boy was take by aliens .
| A．ruled out; that | B．taken out; that |
| C．made out; which | D．ruled out; what |