remain有4种意思,意思不同,用法也不同.
1.作“仍然是,保持”这个意思讲时,和联系动词用法一样.例如：remain silent,He remains (as) boss of the house.
2.作“剩余,遗留”讲,不及物.例如：Very little of the house remained after the fire.
3.作“仍需去做”讲,不及物.例如：It remains to be seen whether you are right.
4.作"逗留,不离开"讲,不及物.例如：The train remained on the statation.
It remains adj that 从句使用频繁.例如：It remains urgent that you should go to hospital at once.
一般来说,remain可以和be动词混用（互相代替）,用法也一致.remain是没有被动的,后面跟to be done和doing这两种情况也很多.
有不懂的话再问~希望能给你带来帮助~