Sunny's uncle is a teacher． _____ enjoys staying with kids．（ ）
A．HeB．SheC．ItD．I
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
Mountain climbing is one of _______ sports in the world．（ ）
A．dangerousB．more dangerous
C．the most dangerous
Are these your books？
No， they aren't． They are _______．（ ）
A．sheB．hersC．her