鸡肉中蛋白质的平均含量大约是（）。
A、15%
B、21%
C、35%
D、40%
参考答案：B
两位老师带着49位学生去郊游，每顶帐篷最多只能住8人．至少需要多少顶帐蓬？
He __________ a letter to his family last Sunday.[ ]
A. wrote
B. write
C. writes
D. has written
