It’s a ____coincidence that the day before his retirement, my English teacher will have been teaching

for a total of forty years.

A. serious

B. cautious

C. curious

D. previous

建国初期为经济建没和社会改革赢得相对稳定的和平环境的事件是[ ]

A．抗美援朝战争

B．土地改革运动

C．三大改造

D．西藏和平解放