have to,must时态的差别．时态上有什么区别have to不能和什么时态一起?

have to,must时态的差别．时态上有什么区别have to不能和什么时态一起? have been to是什么时态? must与must have done 的区别是什么?猜测的时态 现在进行时态与现在完成时的差别 He must have come have yesterday ,didn'he?这里的have是什么意思?这句是什么时态? have has been 是什么时态的havehas been to have的过去时态是什么 She must be sent (must sent) to the hospital时态时态转换是否正确？ she must have been a temporary worker 是什么时态?there has been a tendency to romanticize the accomplishments 是什么时态?是there be 为什么中间有个has? she must have arrived there yesterday .这是什么时态 to have been done是什么时态 have/has+been to是什么时态 have/has+been to是什么时态 I have been to shanghai 什么时态 have的完成时态（have ） His grandma is _____ ill ,so she must be sent to hospitalbad的什么时态? you have to wait until the soup becomes cold时态叫不准，还有所有跟 if 有关的时态问题 时态