The knockout stage of the 2018 FIFA World Cup was the second and final stage of the competition, following the group stage. It began on 30 June with the round of 16 and ended on 15 July with the final match, held at the Luzhniki Stadium in Moscow. The top two teams from each group (16 in total) advanced to the knockout stage to compete in a single-elimination style tournament. A third place play-off was also played between the two losing teams of the semi-finals.
is the round of 16 single elimination in world cup?
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Answer: yes

To become part of the Constitution, an amendment must be ratified by either--as determined by Congress--the legislatures of three-fourths (presently 38) of the states or State ratifying conventions in three-fourths of the states. Thirty-three amendments to the United States Constitution have been approved by Congress and sent to the states for ratification. Twenty-seven of these amendments have been ratified and are now part of the Constitution. As of 2018, the convention process has never been used for proposing constitutional amendments.
has there ever been a convention of states?
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Answer: no

Saint Anthony Falls or the Falls of Saint Anthony, located northeast of downtown Minneapolis, Minnesota, was the only natural major waterfall on the Upper Mississippi River. The natural falls were replaced by a concrete overflow spillway (also called an ''apron'') after it partially collapsed in 1869. Later, in the 1950s and 1960s, a series of locks and dams was constructed to extend navigation to points upstream.
is there a waterfall in the mississippi river?
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Answer:
no