Misc: an LCD is commonly found in calculators etc, what does LCD stand for?

Questions

Czar ---------- banished soldiers to Siberia for marching out of step.?

Czar Paul I banished soldiers to ---------- for marching out of step.?

During the ---------- period, about 500 million years ago, a day was only 20.6 hours long.?

During the Cambrian period, about ---------- years ago, a day was only 20.6 hours long.?

During the Cambrian period, about 500 million years ago, a day was only ---------- hours long.?