轧辊咬入轧件的条件是咬入角（）摩擦角。
参考答案：小于或等于
Only after staying in England for a few weeks did Li Lei become used ____
Chinese.
A．to not speaking
B．not to speaking
C．to not speak
D．not to speak
中国煤炭分类国家标准中，把煤分为哪三大类？
