根據(jù)下列句子的意思及所給單詞的首字母或所給漢語意思,寫出各單詞的正確形式.每空一詞.

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 __________(鼓勵) us to practice English as often as possible.