The science of medicine _______ progress has been rapid lately is perhaps the most important of all the science.
He asked a lot of questions, none of ______ was easy to answer.
He asked a lot of questions, and none of ______ was easy to answer.
He told me that he had two girl-friends, neither of _______ knew anything about the other.
He told me that he had two girl-friends, and neither of _______ knew anything about the other.
All of the flowers now raised here have developed from those _____ in the forest.