存留在外耳道的异物中，对外耳道皮肤和鼓膜刺激最小的是（）异物。
参考答案：刺激较小的非生物性
简述设置培训课程的基本环节。
The first textbooks written for teaching English as a foreign language _____ in the 16th century. [ ]
A. came about
B. came out
C. came along
D. came up
