... otherwise the head of the Senate, Republican Thomas Ferry, would probably have beenallowed to declare the winner. In the end, the Democrats were dis-appointed, as the commission advocated the ... ascertain that the man they arrested was the Gregory Brown they were really looking for. Usage tipsAscertain is often followed by a that clause. Notice that the root of the word is the adjective certain, ... that they obeyed, for Washington’s doctors used the actual smallpox virus, not the safer vaccination that Edward Jenner wouldintroduce in 1798.1.Which sentence best expresses the essential information...