It's six forty in the morning. The children are coming into the classroom.

    A girl is opening the windows. Some are laughing and talking. Some are listening to them. Some are reading books. Some are doing their homework.

Miss Lin is standing behind the teacher's desk. She is writing on the blackboard. Sue and Anna are wearing their new dresses today. Ann is cleaning her desk. Mike is helping her. They all look happy.

    What are Bill and Bob doing? Oh, dear! They are still playing basketball.

读我国土地资源分布图，回答下列问题。

下列属于战国七雄争霸战争的是（     ）

①城濮之战       ②桂陵之战       ③马陵之战       ④长平之战

①选择调查范围

②设计调查路线和方案

③作好记录

④明确调查目的和对象