Story needs to be completed:
He liked using the clippers on the lawn, but ignored the shears, because using the

My choice:
shears was difficult.

Story needs to be completed:
Mary used the calculator to find the solution instead of the abacus, because the

My choice:
abacus was slower for her.

Story needs to be completed:
The bird could lift a string with its beak but not a chain because the

My choice:
string was light.

Story needs to be completed:
The photographer was preparing to take pictures for multiple weddings and replaced the camera but not the lens because the

My choice:
camera was broken.