They do say, " he lowered his voice cautiously, "that it's poison?" Poirot's face remained quite impassive. 
He worried there was poison.
He worried there was no poison to give his enemies.
Try to visit both sites on the same day.
The existence of social security might not lower people's retirement savings.
The boys are cycling.
the pool is frozen solid
There are three dogs in the grass
A man and his cat are walking down the street.