Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Ex Input:
In machines that increase force, such as ramps and doorknobs and nutcrackers, output is greater is the relation between output and input force.

Ex Output:
In machines that increase force, such as ramps and doorknobs and nutcrackers, what is the relation between output and input force?

Ex Input:
Trichomoniasis is cause by a protozoa.

Ex Output:
Trichomoniasis is cause by what type of pathogen?

Ex Input:
The development of the respiratory system in the fetus begins at about 4 weeks.

Ex Output:
The development of the respiratory system in the fetus begins at about?