随机抽样的具体方法有（） A.间隔随机抽样 B.分层随机抽样 C.分区多级随机抽样

血红素

The nurse is caring for a neonate with congenital clubfoot. The child has a cast to correct the defect. Before discharge, what should the nurse tell the parents

A. "The cast will be removed in 6 weeks. "
B. "A new cast is needed every 1 to 2 weeks. "
C. "A short leg cast is applied when the baby is ready to walk. "
D. "The cast will be removed when the baby begins to crawl. "

器官移植在近年获得较快发展，是何种药物的问世使器官移植后排异反应及死亡率明显下降（）

A.泼尼松

B.甲基泼尼龙

C.环孢素A

D.第四代抗生素

E.B和C

简述卵巢肿瘤的概述。

根据对话内容，从对话下边方框内的选项中选出能填入空白处的最佳选项，并将代表该选项的字母填入横线上。选项中有两项为多余选项。
A: What’s the date today
B: It’s June 16.
A: (16) Then it’s Dragon Boat Festival today, isn’t it
B: Yes. (17)
A: Did you have rice dumplings this morning
B: Sure. (18)
A: I didn’t.
B: What a pity! But I happen to have got some with me. (19)
A: I’d love to. By the way, why do you call it Dragon Boat, Festival
B: Because in China, people race dragon boats this day every year.
A: Oh, I see. (20)
B: Yon are welcome.
A．We Chinese usually eat rice dumplings this day.
B．I hate eating rice dumplings.
C．Thank you for your rice dumpling.
D．I don’t think so.
E．Would you like to have one
F．Already
G．How about you