单选题 John as well as Jack ______ just been back from an important meeting.
A. have B. has C. had D. must have

【正确答案】 B

【答案解析】[解析] 在“A as well as B”结构中，as well as=in addition to，因此句子的谓语应与名词A在人称和数上保持一致而不受as well as的影响。其他类似的结构还有：A together with B；A accompanied by B；one after another；A and not B等。