I didn't believe I could do it ____ I got to the top of Mount Tai．（ ）
A．unlessB．untilC．afterD．as
I _______ Anna since three years ago．（ ）
A．knewB．knowC．have known
If I go to the movie， I _______ my homework on time．（ ）
A．didn't finishB．don't finish
C．won't finish
I like Chinese， _______ I don't like math， because it's not easy to learn it well．（ ）
A．andB．butC．or
I think it's impolite _______ others waiting．（ ）
A．to keepB．keepingC．keep
I cleaned my room yesterday． It _______ a little difficult．（ ）
A．isB．wasC．will be