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.