1.No left turn. 2.No parking. 3.You must be carefui. 4.You must look both ways before crossing the road. 5. You should be quiet in the reading room.
我觉得那些也是祈使句呀,还有祈使句的变法
祈祈句的标准 构成是 动词放在最前面或否定时把Don't放在最前面所以上面只是一些标语,并不是标准的祈使句