Mary ________ as a secretary in this company for twenty years and now she stays at home taking care of her own garden.
| A．has served | B．had served |
| C．is serving | D．served |
It was with the selfless help of our teacher ______ we realized our dream.
| A．that | B．who | C．when | D．how |
To build a harmonious society, we all have a part to play in the fight ____ injustice, unemployment and crime.
| A．over | B．by | C．for | D．against |
This chemical material is very toxic. So put it ______ the children’s reach.
| A．by | B．beyond | C．within | D．from |
The central heating system of this office building is down and several workers ______ it right now.
| A．had repaired | B．have repaired | C．repaired | D． are repairing |
China's present environment situation is from bad to worse and if we _________ now to protect the environment, we’ll live to regret it.
| A．hadn’t acted | B．haven’t acted | C．don’t act | D．won’t act |