—Who’s in the room? — Mr. Brown is. He a letter now. A. writesB. writeC. writingD. is writ

问题补充：

—Who’s in the room? — Mr. Brown is. He a letter now.

A. writes

B. write

C. writing

D. is writing.

答案：

A. writes

B. write

C. writing

(答案→)D. is writing.

解析：句意：——谁在房间里？——布朗先生。他现在正在写信。根据时间副词now可知此处用现在进行时be doing, 因为主语是he, 故谓语用is writing,故选D。