用a, an, the 或/填空, 每词不限用一次
（1）、There is picture of elephant on wall.
（2）、Let's go out for walk.
（3）、It's too hot. Open door, please.
（5）、This is useful book. I've read it for hour.
（6）、Do you like to play piano or play table tennis?
（7）、My parents usually have breakfast at 7 in the morning.
