He _____ English for ten years by the time he takes the examination.

A．will have been studying

B．would have been studying

C．will study

D．studied

战后科技革命对发达资本主义国家和全世界的生产力发展所起的推动作用，更是十分巨大的，充分体现了“科学技术是第一生产力”。主要表现有（）

A．极大地提高了劳动生产率

B．扩大了资本积累

C．增加了就业

D．保证了劳动力的供应