一次函数y=x+2的图象不经过第______象限．
∵1＞0，2＞0，
∴一次函数的图象经过一、二、三象限，即不经过第四象限．
阅读短文，回答问题。
Li Ming is a Chinese boy. He wants to study in Canada. He wants to learn English for ten months.
He will live in Jenny's home. Jenny is his friend. She is a lovely girl. She introduces (介绍) her house
to Li Ming. There are six rooms in her house. They are three bedrooms, a living room, a kitchen and
a bathroom.
1.Where does Li Ming come from ?
_____________________________________________
2.Where does Li Ming want to study?
3.What does Li Ming want to learn ?
4. How many rooms are there in Jenny's house ?
在下图所示双代号时标网络计划中，如果C、E、H三项工作因共用一台施工机械而必须顺序施工，则该施工机械在现场的最小闲置时间为（）周。
A．4
B．3
C．2
D．1
