【单选题】The teacher was a little angry because the students didn't _____ their exercise books on time. [ ]
【单选题】The students didn't stop talking _______ the teacher came in. [ ]
【简答题】在图示轮系中,已知:蜗杆为单头且右旋,转速 ,转动方向如图示,其余各轮齿数为 ,试: (1)说明轮系属于何种类型; (2)计算齿轮4的转速 ; (3)在图中标出齿轮4的转动方向。
【多选题】下列哪种样品可用常压干燥法(AG),应用减压干燥的样品是(CDF)应用蒸馏法测定水分的样品是( )。
【单选题】The students didn't stop _____until the teacher entered the classroom
【单选题】The students didn't find much ___ about the topic on that website.