Mark needs to learn Chinese his company is opening a branch in Beijing.A. unlessB. untilC

问题补充：

Mark needs to learn Chinese his company is opening a branch in Beijing.

A. unless

B. until

C. although

D. since

答案：

A. unless

B. until

C. although

(答案→)D. since

解析：句意：马克需要学习汉语，因为他的公司正在北京开一个分公司。A除非；B直到；C尽管；D因为。故选D。