He is brave, hard-working and kind, so he was elected ________ monitor of our class.
Two people were killed in the serious car _______ the other day.
It is said that the temperature is unusual mainly _______ global warming caused by human activities.
The transformation of our city will make _______ for people here to have a comfortable environment.
Mary _______ her mother with the housework, but she didn’t.
The local government announced that only when the fire was under control ________ to return to their homes.