Is "在" necessary in this case?
In English we use be+ verb (ing form) to indicate present, continuous action. In Chinese my understanding is that 在 is used somewhat similarly, like in the sentence below:
医生在诊患者
My question is: Is it also grammatically correct to simply say: 医生诊患者 (ie., leave out "在")?
Or, to put it another way, is "在" REQUIRED in such a sentence? If we leave it out does it change the sense, or make the sentence simply wrong, grammatically speaking?