用数字表示每台内燃机具有的汽缸数目，一般放在型号的（）。
A.随便位置
B.中部
C.后部
D.首部
参考答案：D
I shall never forget those years ______ I lived in the country with the farmers, ______ has a great effect on my life.
A．that; which
B．when; which
C．which; that
D．when; as
肛柱下端半月形的粘膜皱襞称______。
