QUES: Notably, a statute does not disappear automatically merely because it has been found unconstitutional; it must be deleted by a subsequent statute. Many federal and state statutes have remained on the books for decades after they were ruled to be unconstitutional. However, under the principle of stare decisis, no sensible lower court will enforce an unconstitutional statute, and any court that does so will be reversed by the Supreme Court. Conversely, any court that refuses to enforce a constitutional statute (where such constitutionality has been expressly established in prior cases) will risk reversal by the Supreme Court.

What can delete a statute and make it unconstitutional?
What is the answer?
ANS: a subsequent statute
QUES: From the 1950s on, the students were also used for unpaid work at schools, where they cleaned and performed repairs. This practice has continued in the Russian Federation, where up to 21 days of the summer holidays is sometimes set aside for school works. By law, this is only allowed as part of specialized occupational training and with the students' and parents' permission, but those provisions are widely ignored. In 2012 there was an accident near city of Nalchik where a car killed several pupils cleaning up a highway shoulder during their "holiday work" as well as their teacher who was supervising them.

What year were students killed as part of a road cleanup project?
What is the answer?
ANS: 2012
QUES: These areas contain some spectacular scenery as well, as evidenced by such national parks as Yosemite and Mount Rainier. West of the Cascades and Sierra Nevada is a series of valleys, such as the Central Valley in California and the Willamette Valley in Oregon. Along the coast is a series of low mountain ranges known as the Pacific Coast Ranges. Much of the Pacific Northwest coast is inhabited by some of the densest vegetation outside of the Tropics, and also the tallest trees in the world (the Redwoods).

What are the skinniest trees in the world?
What is the answer?
ANS:
unanswerable