A child washes rocks in a small tub .
A child washes dirty laundry in a large tub
A child washes rocks in a small tub.
A child washes dirty laundry in a large tub
If the child is washing rocks, then it can't be washing laundry. The tub cannot be small and large at the same time.
If the child is washing rocks , then it ca n't be washing laundry . The tub can not be small and large at the same time .