— Please inform all of them. I hope everyone will be able to join in the activity.
— OK. I'll do it right away.
A:give up
B:take part in
C:believe
先填空,再写出本题的数量关系.
某服装厂生产一批学生服.每天生产250套,8天完成.这批学生服一共____套.
工效×____ =____
如图所示,用一动滑轮把100N的沙子匀速提到3m高处,作用在绳末端的拉力为60N,则滑轮组的机械效率为 ( )
①石墨 ②干冰 ③尿素 ④明矾 ⑤硝酸钾 ⑥肥皂水