The US court system, as part of the federal system of government, is characterized by dual

hierarchies; there are both state and federal courts. Each state has its own system of courts,composed of civil and criminal trial courts, sometimes intermediate courts of appeal, and a state supreme court. The federal court system consists of a series of trial courts (called district courts) serving relatively small geographic regions (there is at least one for every state), a tier (系列, 等级) of circuit (巡回) courts of appeal that hear appeals from many district courts in a particular geographic region, and the Supreme Court of the United States. The two court systems are to some extent overlapping, in that certain kinds of disputes (such as a claim that a state law is in violation of the Constitution) may be initiated in either system. They are also to some extent hierarchical, for the federal system stands above the state system in that litigants (诉讼当事人) (persons engaged in lawsuits) who lose their cases in the state supreme court may appeal their cases to the Supreme Court of the United States. Thus, the typical court case begins in a trial court—a court of general jurisdiction (司法) in the state or federal system. Most cases go no further than the trial court: for example, the criminal defendant is convicted (by a trial or a guilty plea) and sentenced by the court and the case ends; the personal injury suit results in a judgment by a trial court [or an out-of-court settlement by the parties while the court suit is pending (悬而未决的)] and the parties leave the court system. But sometimes the losing party at the trial court care enough about the course that the matter does not end there. In these cases, the "loser" at the trial court may appeal to the next higher court.

What does the passage mainly discuss？

A．Civil and criminal courts.

B．Typical court cases.

C．The court system in US.

D．The appeal court process.