A summary of the questions answered, and still pending, about the disappearance of Malaysian Airlines Flight 370 after Malaysian Prime Minister Najib Razak's Monday announcement:What we knowTHE PLANE CRASHED: Najib said satellite data showed the flight "ended in the southern Indian Ocean," confirming that the Boeing 777 that disappeared more than two weeks ago went down in a remote corner of the ocean, "far from any possible landing sites." ITS LAST POSITION: A British company calculated satellite data obtained from the remote area of the ocean, using analysis never before used in an aviation investigation of this kind, and pinpointed the last spot the flight was seen in the air was in the middle of the ocean west of Perth, Australia. NO SURVIVORS: Najib left little doubt that all 239 crew and passengers had perished in the crash; the father of an aviation engineer on the flight said, "we accept the news of the tragedy. It is fate."What questions remainWHO AND HOW: Malaysian authorities have not ruled out any possible explanation for what happened to the jet, but have said the evidence so far suggests it was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next. Authorities are considering the possibilities including terrorism, sabotage, catastrophic mechanical failure or issues related to the mental health of the pilots or someone else on board. WHAT'S FLOATING IN THE OCEAN: The prime minister didn't address whether investigators had confirmed floating objects in the ocean and images captured by several countries' search parties, including that of France and China, were debris from the plane.