Not only his parents but also his brother to the Summer Palace. They will be back next wee

问题补充：

Not only his parents but also his brother to the Summer Palace. They will be back next week.

A. have been

B. have gone

C. has gone

D. has been

答案：

A. have been

B. have gone

(答案→)C. has gone

D. has been

解析：不但他的父母而且他的兄弟都去了颐和园，下一周将返回，表示某人去了某地在路程当中通常用have或has gone to+地点，not only……but also作主语时谓语动词采用就近原则，最近的是单数第三人称his brother，故谓语部分中的助动词用has，故选C。Have或has been表示某人去过某地，现在不在外地，与本题意思不符。