问题 单项选择题 B型题

主要根据暴露状况来抽取样本的研究是()

A.描述性研究

B.队列研究

C.病例对照

D.实验性研究

E.理论性研究

答案

参考答案:B

选择题
句型转换

将下列句子改成祈使句,并将其改为祈使句的否定形式。

1、They come to the front and point to me. 

                                                             

                                                             

2、You can sit on this seat.

                                      

                                      

3、He is listening to music.

                                       

                                       

4、You are a good man.

                                 

                                  

5、He is cleaning the classroom. 

                                              

                                              

6、She can wash clothes for her grandma. 

                                                            

                                                            

7、You should stay at home today. 

                                                

                                                

8、Tom can answer my questions. 

                                                  

                                                  

9、You would like to read the new words for us.

                                                                    

                                                                      

10、They are sweeping the floor. 

                                              

                                              

11、You did your homework carefully. 

                                                       

                                                       

12、They can take bus No. 5 to No.  1 Middle School. 

                                                                             

                                                                             

13、You should do it again.