1.Researchers have found clear and convincing evidence ________ happiness is
the key to better health and longer lives.
A. where B. whether C. how D. that
【答案】D
【解析】考察同位語(yǔ)從句.同位語(yǔ)從句that happiness is the key to better health and longer lives解釋名詞evidence的內(nèi)容。