流程图也称为程序框图是最常用的一种表示法，它有顺序、分支和（）三个基本控制构件。
参考答案：循环
Before we went into the museum, we _____ not to touch the things on show. [ ]
A. told
B. tell
C. were told
D. are told
鲸、海牛的牙列为（）
A.单牙列
B.多牙列
C.端生牙
D.同形牙
E.异形牙
