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

[EX Q]: Ultrasound, a diagnostic technology, uses high-frequency vibrations transmitted into any tissue in contact with the transducer.
[EX A]: What diagnostic technology uses high-frequency vibrations transmitted into any tissue in contact with the transducer?

[EX Q]: Pangaea began breaking apart 250 million years ago.
[EX A]: How many millions of years ago did pangaea begin breaking apart?

[EX Q]: If two chlorine atoms share their unpaired electrons by making a covalent bond and forming cl2, they can each complete their valence shell.
[EX A]:
If two chlorine atoms share their unpaired electrons by making a covalent bond and forming cl2, they can each complete their what?