根据下列句子的意思及所给单词的首字母或所给汉语意思,写出各单词的正确形式.每空一词.

1. The food smells d_________________. Why not go to taste it?

2. Please take the m_________ three times a day, and you’ll be OK soon.

3. There is too much n__________. Let’s find a quiet place to rest in. 

4. By the end of the _______(二十) century, the world population had passed six billion.

5. My teacher often __________(鼓励) us to practice English as often as possible.