疏散清宣滑利，能外散风热，内解热毒，上宣肺气，下利二便的药
A．葛根B．柴胡C．牛蒡子D．荆芥E．桑叶
参考答案：C
—Mom, my classmates invited me ____ a field trip. May I go with them?
—OK.[ ]
A. go on
B. to go on
C. go in
D. to go in
单根羊毛的宏观形态特征是怎样的？羊毛纤维从外向内有哪几层组成？各层的结构特征如何？
