It is a rule in our school that no books should be taken out_____（带出）unless you have a library card.
不需要用虚拟
因为这是一个事实不用should be taken out 吗？我填的不就是should be taken out吗can be taken out 这是你刚才的答案。我不知道哪个对。我没有填过can be taken out两个都是可以的should更好有一种应该的意思