问题 单项选择题

()调速具有过载能力大,调速比大,起制动性能好,适合频繁的起制动,事故率低等优点

A.直流调速

B.交流调速

C.变频调速

答案

参考答案:B

填空题

Read and write. 仿照例子,写出动词的不同形式。

Yesterday                                     Today                                           Tomorrow 

 worked                                        work                                             will work 

                                                     see                                                             

 bought                                                                                                            

                                                                                                         will open

                                                    teach                                                                                                

                                                     eat                                                               

单项选择题 B1型题