An American scientist and writer coming to give us a lecture on English learning methods

问题补充：

An American scientist and writer coming to give us a lecture on English

learning methods when he visits our school.

A. was

B. were

C. is

D. are

答案：

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。