根据句意及汉语提示完成句子。

1.Her____（口头的）English is very good.   

2.My sister is_____（害怕）to speak English with other people.    

3.At last, he_____（意识到）he was wrong.

4.Memorizing so many words in twenty minutes is a great_____（挑战）for me. 

5.Be sure of me. I won't tell your_____（秘密）to others.

只需过滤推动力能克服过滤阻力，过滤操作就能进行。