—That's a great sweater.I have never seen anything like it before.

—You think so? My grandmother ________ it for me. （   ）

如图所示的动滑轮，拉着物体M以0.5m/s的速度在水平面上做匀速直线运动，物体重200N，它受到的摩擦力是物重的0.2倍，水平拉力为25N．2s内拉力做的功是　 ____J，该动滑轮的机械效率是 ____

阅读下面的诗，回答相关问题。

                                                                                         《宣州谢脁楼饯别校书叔云》
                                                                      弃我去者，昨日之日不可留；乱我心者，今日之日多烦忧。
                                                                      长风万里送秋雁，对此可以酣高楼。蓬莱文章建安骨，中间小谢又清发。
                                                                      俱怀逸兴壮思飞，欲上青天揽明月。抽刀断水水更流，举杯销愁愁更愁。
                                                                      人生在世不称意，明朝散发弄扁舟。
                                                                                           《渡荆门送别》
                                                                        渡远荆门外，来从楚国游。山随平野尽，江入大荒流。
                                                                        月下飞天镜，云生结海楼。仍怜故乡水，万里送行舟。