证明：在一个三角形中，至少有一个内角小于或等于60度．

下图为某同学“探究牛顿第一定律”的实验装置．实验中该同学先后三次将同一木块放在同一斜面上的同一高度，然后分别用不同的力推了一下木块，使其沿斜面向下运动，逐渐减小水平面的粗糙程度，观察木

块运动的距离，从而得出力和运动的关系。

Sally: Good afternoon, Jenny.

Jenny: Good afternoon, Sally.

Sally: Oh, Jenny, this is my aunt Alice. Alice, this is my friend Jenny.

Jenny: Nice to meet you, Alice.

Alice: Nice to meet you, too, Jenny. Your school is very good. I like (喜欢) it.

Jenny: I like it, too.

Sally: Jenny is a good English teacher. Her students (学生) like her.

Jenny: Thank you, Sally.

Alice: Well, have a good day!

Sally & Jenny: Thanks. You, too. Bye.

根据材料内容判断正误。