电控燃油喷射系统的闭环控制与开环控制是根据有无（）来区分的。

根据短文及首字母提示填入恰当的单词完成短文。

Dear Ted,    

       Thank you for your i  1    I can't v  2   you this week because I'm very busy. This afternoon I have to go to the c  3   with my brother. You know I like music very much. And on T  4  ，I have to help my brother with his c  5   because he isn't good at chemistry. On Wednesday, I'm having volleyball t  6   with my friends. And on Thursday evening,I have a piano l  7  . I have to help my mother b  8   my sister on Friday.    On w  9  , I'm going to Hong Kong for v  10  . Can you go to Hong Kong with me?

Write soon.

                                                                                                                                                    David

退变性脊椎滑脱症需与椎弓根性脊椎滑脱症鉴别，后者的特点是（）

A.滑脱程度常较重

B.常伴有椎间盘突出

C.椎弓根峡部的单侧或双侧断裂

D.椎管前后径常有明显增宽

E.椎管前缘与棘突后缘间距增大

【诗配画】如果请你为一本以思乡为主题的诗集设计一个封面，下面哪幅图片可供选择？请说明理由。（2分）

A                     B                         C

我选择：        理由是：                                               

三相绕线式感应电动机启动时为了减小启动电流并增加启动转矩，可通过（）启动。

A.定子串接电抗器

B.自耦降压启动器

C.Y-△降压启动器

D.转子串接电阻

E.频敏变阻器

简述复式梯线的优缺点和适用条件？