在神经调节方面,人类区别于动物的特点是[ ]
A.人能对语言、文字的刺激发生反应
B.人的大脑皮层具有语言中枢
C.人能有目的进行社会性劳动和生活
D.以上三种特点都是
答案:D
正在修建中的港珠澳大桥全长约50公里,中间段是6公里长的海底隧道。港珠澳大桥中部建设成海底隧道,主要是为了( )
A.便于大型轮船通行
B.缩短通行距离
C.加大桥面的宽度
D.减小施工难度
He _____ football regularly for many years when he was young. [ ]
A. was playing
B. played
C. has played
D. had played