In Chicago, fires destroyed at least 20 buildings. 1968: United States erupts in race violence England have Dozens of major cities in the United States have been rocked by an escalation in the race riots which began two days ago. At least 19 people have died so far in the arson, looting and shootings provoked by the assassination of black civil rights leader Martin Luther King on 4 April. Several hundred have also been injured and about 3,000 people have been arrested - most of those in Washington DC. Curfews are in place in many areas of the country and National Guard soldiers have been mobilised to help quell the violence which is threatening to engulf the US in a race war. Twelve thousand troops in the nation's capital were called on to help protect fire fighters tackling at least eight blazes started by rioters. Other fires started in Chicago were accompanied by looting and sniping, and at least 20 buildings have been completely destroyed. There have also been 38 arson attacks in Detroit, shootings reported in Pittsburgh and a four-hour gun battle at Tennessee State University. For every Martin Luther King who falls, 10 white racists will go down with him United Black Front chairman Lincoln Lynch Dr King's immediate successor, Reverend Ralph Abernathy, has repeatedly appealed for calm. The new head of the Southern Christian Leadership Conference of Atlanta has appeared on television urging people to respect the murdered leader's commitment to non-violent protest. But United Black Front chairman Lincoln Lynch said black Americans should adopt a new stance. "It is imperative to abandon the unconditional non-violent concept expounded by Dr King and adopt the position that for every Martin Luther King who falls, 10 white racists will go down with him. "There is no other way - America understands no other language," he said. A national day of mourning in the US for Dr King will take place on 7 April.

Juvenal Habyarimana and his Burundian counterpart both died. 1994: Rwanda presidents' plane 'shot down' Artificially 1969: The The presidents of the African states of Rwanda and Burundi have been killed in a plane crash near the Rwandan capital, Kigali. Juvenal Habyarimana of Rwanda and Burundi's Cyprian Ntayamira were among 10 people on the aircraft which some reports say was brought down by rocket fire. The two presidents were returning from a meeting of east and central African leaders in Tanzania at which they discussed ways to end the ethnic violence in Burundi and Rwanda. Bloody feuding between the majority Hutu tribe and the minority Tutsis has plagued both tiny central African states for centuries. It has been particularly bad in Burundi where up to 100,000 people have been killed since the assassination of the country's first democratically-elected president - a Hutu - last October. In Rwanda, President Habyarimana's Hutu coalition reached a peace accord last August with Rwandan Patriotic Front (RPF) rebels, made up mainly of Tutsis, but they have failed to agree on a transitional government. The deaths of the presidents, both Hutus, looks likely to make the situation in both states worse. Heavy fighting has already been reported around the presidential palace in Rwanda after news of the deaths spread. News agencies in Kigali said explosions have been rocking the city but it was not immediately clear who was involved in the fighting. 'Assassination' Rwanda's ambassador to the United Nations, Jean Damascene Bizimana, said the presidents' deaths had been an "assassination". Members of the UN Security Council held a minute's silence for the presidents and later appealed for calm while the crash was investigated. From 1890 until 1962 Rwanda and Burundi were one nation, Ruanda-Urundi. It was under the control of first Germany and later Belgium. The Belgians supported Tutsi kings' rule over the Hutu majority - worsening the bad feeling between the tribes.

Vocabulary:

imperative: expressing a command or plea; peremptory（命令的, 紧急的, 必要的） feud : a bitter, often prolonged quarrel or state of enmity, especially such a state of hostilities between two families or clans.（长期不和）