It never _____  humans until the mid­1990s that some animals can be cloned.

It wasn’t until nearly a month later          I received the manager’s reply.

_____ is no need to argue again the problem.We settled it at the last meeting.

_________ no doubt that a green campus plays an important role in the growth of students, both physically and mentally.

(2014·苏锡常镇四市调研)—As a teenager，our son should have two or three hobbies to be really happy.—________，but how can he afford the time with so much homework every day?