However, not every experiment requires it, so you can get started right away.

The "American experiment" has, from its very beginnings, required the rule of law.

This experiment does not require a radical feat of the imagination.

Yet the forthcoming experiment had required considerable time for preparation.

Thus, according to general consensus, these experiments require ethical justification.

It seemed to me that experiments of such a nature, to have any value at all, would require a rather enormous setup.

It's set up to allow someone to spend the night at the lab if an experiment requires it.

Our own experiments require it, and anyway I've burned too many bridges here in the past few days to stop now.

The problem was that the facilities and experiments required giant sums of money.

The experiment I am about to start now will require 15 test sessions per subject, each about two hours.