常用的抽样方法中，分层抽样的优点是（）。 A.便于组织、节省经费 B.易于理解、简便
题型：单项选择题
问题：
常用的抽样方法中，分层抽样的优点是（）。
A.便于组织、节省经费
B.易于理解、简便易行
C.样本代表性好，抽样误差减少
D.操作简单，均数、率及相应的标准误计算简单
题型：单项选择题
Harry came in a minute after James. There was a letter for him, too, which he opened at once. It was from the secretary (秘书) of a company, offering him a post (职位) in their office. He was told to be there at 10 a. m. the next morning, as there were others who wanted the job.
James got back from the play at midnight. He was sleepy. “That letter can be opened in the morning,” he thought. The next morning when he woke up, he at once jumped out of bed, tore(撕)it open-his face fell. It was a similar letter to the one Harry had received the night before. But James’ chance was gone. It was five to ten, and he could never be at the office in time.
小题1:One evening James came in in a great hurry because .
A．he knew there was a letter on the hall table
B．he had to tell someone to keep his letter until he got back
C．he was afraid he would be late for the play
D．his friend was waiting for him outside the hotel小题2:As soon as he woke up，James .
A．wondered where Harry had gone
B．was eager (急切的) to know the time
C．knew he could never be at the office in time
D．remembered the letter from the company小题3:The underlined sentence “his face fell” in the passage means“ ”.
A．he knew there was something wrong with his face
B．he felt very sorry for missing the chance
C．he fell down on his face
D．he realized that he had lost his face