A:质量50kg
B:身高160m
C:体温37℃
D:步行速度1m/s
下列关于法定义务的说法,正确的是( )
A. He is sending an email to his friend.
B. This dress is for Amy.
C. The boys are playing football.
D. This girl is writing a letter.
E. We had a happy time in the park.
(____)
(____)
冬小麦是我市重要的粮食作物之一,栽培历史悠久,品质优良。请根据研究冬小麦过程中所遇到的有关问题作答: