One of the suspects is _________ schoolboy.
A:a 18-year-old
B:a 18 years old
C:an 18-years-old
D:an 18-year-old
A)根据汉语意思完成英语句子,每空一词。
种子萌发的必要条件是具有____的胚.
480-(48+48÷16)
=480-(48+3)
=480-51
=429