胃壁在声像图上可显示的结构层数有（）。
A.6层
B.5层
C.4层
D.3层
E.2层
参考答案：B
Could you tell me ______? [ ]
A.when shall we start
B.who are you waiting for
C.where the nearest bus stop is
D.why were you late
请说明备课的基本要领有哪些？
