题目内容：

关于be supposed to do
the security of the babies is supposed to ___ by the nurses.
为什么是 be seen to 而不是 be seen?

优质解答

这里是词组see to的被动式,意思为“照料,看管,负责”,see to是个词组,类似deal with,see about,take care of,look after.
我们用还原法来做：The nurses is supposed to see to the security of the babies.