根据句义和所给汉语提示完成句中所缺的单词.
1. There are four __________ (字典) on the table.
2. February is the __________ (第二) month in a year.
3. The shoes are very nice, but I can not __________ (买得起).
4. Running star Sandra eats lots of __________ (健康的)food.
5. Math is very __________ (困难的), I can not learn it well.
1. dictionary
2. second
3. afford
4. healthy
5. difficult