四个
The decision about such a big project cannot be made _____ each member of the board agrees.
The decision about such a big project cannot be made \_\_\_\__ each member of the board agrees.
改革开放以来，我国主要区域政策经历了不同的阶段：①以经济特区为重心的沿海地区优先发展阶段；②以缩小区域差距为导向的西部大开发阶段；③以浦东开发为龙头的沿江沿边地区重点发展阶段；④以区域协调发展为导向的共同发展阶段。这四个阶段按时间顺序排列应为（ ）。
改革开放以来，我国主要区域政策经历了不同的阶段：①以经济特区为重心的沿海地区优先发展阶段；②以缩小区域差距为导向的西部大开发阶段；③以浦东开发为龙头的沿江沿边地区重点发展阶段；④以区域协调发展为导向的共同发展阶段。这四个阶段按时间顺序排列应为（ ）。
The best title for the passage is _____.
The best title for the passage is \_\_\_\__.
Now the air pollution in this city _____ more and more serious with each passing day.
Now the air pollution in this city \_\_\_\__ more and more serious with each passing day.
In order to improve your communication skills, we will show you how to learn _____ about your customers than you know now.
In order to improve your communication skills, we will show you how to learn \_\_\_\__ about your customers than you know now.
_____ you choose to contact us, you can expect our efficient and helpful service.
\_\_\_\__ you choose to contact us, you can expect our efficient and helpful service.