“21世纪”用英语怎么写?

21世纪twney-first Century
112房间 Room 112
12个婴儿ywelve babies
15只鸟fifteen birds
在6：30at half past six
数百所学校hundreds of schools
36天thirty days
第九周the ninth week
在9：15at a quarter past nine

21世纪 twenty-one century
112房间 room 112
12个婴儿 twelve babys
15只鸟 fifteen birds
在6：30 at six-thirty
数百所学校 hundreds of schools
36天 thirty-six days
第九周 ninth week
在9：15 at nine-fifteen

the twenty-first century
Room one one two
twelve babies
fifteen birds
at half past six
hundreds of schools
thirty-six days
the ninth week
at a quarter past nine
lesson one