This is a kind of effective classroom teaching ______ students learn independently and cooperatively.
. When you copy this paper, be careful not to ______ a single word.
. Why does she steal things ________ she could easily afford to buy them?
. My parents would have come to see you if it had been possible, but they ________ so busy.
. Mary is a(n) _______ customer, so the waiter knows her likes and dislikes.
. Recently I bought a ticket for Shanghai World Expo, _______ was very reasonable.