词形转换，用括号内所给单词的适当形式填空，毎空格限填一词。
1.Li Ma is an outstanding tennis ___________ (play).
2.Be __________ (care) when you cross the street.
3.October is the ___________ (ten) month of the year.
4.Recently, scientists have found that dogs are ___________ (smart) than cats.
5.Such an important problem should be discussed __________ (serious).
6.Anna had a fever yesterday, so she was __________ (able) to go to school.