根据括号内的汉语提示，完成句子。

1. He didn't _____ (认识到) that he had lost his way until it was very dark.

2. We can't learn English well _____ (除非) we put our heart into it.

3. If you want to be a good speaker, you have to pay attention to your _____ (发音).

4. We are always _____ (面对) different kinds of challenges.

5. Be more _____ (耐心的), then you will succeed in the end.

6. Lei Feng, one of the greatest _____ (士兵), set us a good example.