单选题
You ______ him so closely ; you should have kept your distance. A. shouldn't have been following B. mustn't follow C. couldn't have been following D. shouldn't follow
【正确答案】
A
【答案解析】[解析] 在某些暗含虚拟条件的简单句中，虚拟语气可通过上下文表现出来。谓语动词用should/would be型或should/would have been型虚拟形式。