单选题 John is collaborating with Mary in writing an article
A. cooperating
B. competing
C. combining
D. arguing

【正确答案】 A

【答案解析】collaborate：合作；勾结；cooperate：合作。 She has agreed to cooperate with the police in the investigation. 她同意在调查中跟警察合作。compete：竞争。combine：合并；argue：争论。