根据首字母或汉语提示填空。

1．Many students find it very difficult to m            English words.

2．Lucy can write English very well, but she must pay attention to her p            and try to speak it better.

3．Just now I r            that I had left my schoolbag on the playground.

4．This exam is a real c           . Please study hard for it.

5．Although I failed four times, my father encouraged me to have a f            try.

6．In my d            life, reading newspapers has become a part of mine.

7．He used to be a "problem child", but recent c            changed his life.

8．Our teacher listed three p            on how to write a good essay.

9．Luckily, she has an o            to make an advanced study in Beijing.

10．Most children can not c            on one thing for a long time.

一侧颈内动脉闭塞，可无临床症状，是因为（）。

A.同侧颈外动脉未闭塞

B.对侧颈内动脉未闭塞

C.正常脑底动脉环可迅速建立侧支循环

D.双侧椎动脉未闭塞

E.颅内血管变异