China’s building firms are__________ to expand their business ab

China’s building firms are__________ to expand their business abroad.
A、doing efforts
B、making efforts
C、doing effects
D、making effects
【正确答案】：B
【题目解析】：make efforts to do sth. 努力做某事，根据句子的意思“中国的建筑公司正努力扩展他们的海外业务”，因此选择B选项。