题目

按要求完成句子。 （1） His books are in the schoolbag. （否定句）His books in the school bag. （2） My sister plays tennis after class. （一般疑问句） your sistertennis after class? （3） We like science because it is difficult but interesting. （对划线部分提问）you like science? （4） Her father is forty years old. （对划线部分提问） is her father? （5） Those are his radios. （变为单数句） his . （6） Jack has some comic books at home (改为一般疑问句) Jackcomic books at home? 光滑圆柱体放在V形槽中，截面如图所示，它的左边接触处为A，V形槽间夹角为2α(2α＞90°)．用一细绳拴住V形槽，另一端通过定滑轮拴住一重物．设圆柱质量为m，槽的质量为M，不计各种摩擦和滑轮的质量，当质量足够大时，在运动中圆柱体可以从槽中滚出，欲使圆柱体在运动中不离开V形槽，则重物，应满足什么条件？