下列导游员运用手势不当的是（）。
A、富于变化
B、因人而异
C、简洁易懂
D、强劲有力
参考答案：D
分别画出四幅图中反射、入射或折射光线的可能传播方向．
-What do you think of maths?
-My favourite. It's ________ for me to study of all the subjects in school.[ ]
A. more difficult
B. the most difficult
C. less difficult
D. the least difficult
