______ is often the case in science, there is no simple answer

We'll carry on the work ______ we can get the machines we need. After all, it's the determination that really counts.

 ________ the calculation is right, scientists can never be sure that they have included all variables and modeled them accurately.

.---______?------- That would be great! Please drop me off at the library.

When you get on stage for the first time, you may be surprised by ______bright the lights are.