Tom, clean up the broken glass _________ someone walks on it.
A lot of environmentalists argue ___________ a strong control over the poultry(家禽)industry in order to prevent further Bird Flu cases.
Hie risk of heart disease is a powerful argument ___________ smoking.
It is a serious novel, not ___________.
We go for a walk in the fields ___________, but not often.
Don't be rude to your father. Never in his life ___________ that way.