未知题型 Though he was born and brought up in America, he can speak ___________ Chinese.A)fluid B) smooth C) fluent D) flowing

未知题型 The fire was finally brought under control, ___________ extensive damage had been caused.A) before B) since C) after D) as

未知题型 As a public relations officer, he is said ________ some very influential people.A) to know B) to be knowing C)to have been knowing D)to have known