问题
选择题
Discovery in a South African cave suggests that modern human behavior ____ much earlierthan ____.
A．begin, previously thought
B．began, previously thought
C．should begin, previous thinking
D．began, previous thinking
答案
答案：B
题目分析：考查时态及非谓语动词。句中的动词suggest为“表明”之意，故从句用真实语气，根据时态用一般过去时；逻辑主语modern human behavior与think为被动关系，故用过去分词，分词前只能用副词修饰。句意：在南非一个岩洞发现表明，现代人类行为的开始要比先前认为的要早的多。故B正确。