Unwilling to give up slavery, the South_____ from the Union and set up a state of their own, resulting in the American Civil War. [ ]

26．Newly-developed materials for spaceships can______extreme weather conditions.

____ I take the book out?—- I’m afraid not.

下列各句中，表达得体的一句是

I believe that human cloning is wrong. If we toy with nature, we will have to deal with the _______.