An American scientist and writer ing to give us a lecture on English
learning methods when he visits our school.
A. was
B. were
C. is
D. are
网友回答
A. was
B. were
(答案→)C. is
D. are
解析：考查时态及主谓一致。句意：当他参观我们学校时，一位美国科学家兼作业来给我们做一场关于英语学习方法的演讲。结合语境可知本句描述的是客观存在的事实，故用一般现在时态。联系下文可知科学家和作家指的是一个人，故谓语动词用单数，选C。