--This kind of sports is exciting.
--Yes,but it's dangerous.One can't do it ____ he or she has got some training.
A.if | B.after | C.when | D.Unless |
--This kind of sports is exciting.
--Yes,but it's dangerous.One can't do it ____ he or she has got some training.
A.if | B.after | C.when | D.Unless |