Teenagers can't afford to buy expensive gifts. So what do you do if you want to give gifts to the important people in your life? In fact, you don't have to spend much money on holiday gifts. There are many cheap ways to do that. Here are some make-it-yourself gift ideas to try:

To your mom and dad:

    You can clean the room, sing a song or write a letter to your mom and dad. You could also draw a picture if you like.

To your teacher:

    Sometimes students put their pocket money together and buy a teacher a holiday gift. Some kids would like to give their own gifts. You can send a nice card with the words of thanks inside. You might even write down the favorite things you've learned in the teacher's class this year. It will make the teacher feel happy.

To the kids who need a friend:

    The holidays are a good time to think about people who are lonely. Maybe there is someone in your class who doesn't seem to have any friends. Try to do something for this person. It could be giving a Christmas card or just chatting with him or her. It's a small thing, but it could mean a lot to him or her.

①花坛里开满了鲜花。（修改病句）

②你错了。你应该第一个伸过手去请他原谅。（用关联词合句）

③二福练出个“单臂倒立”的绝技。（改为“被”字句）

④速算  练会  的  小柱子吧  绝招  （连成一句通顺的话，并加上标点）

下列哪个例子不能说明力能使物体发生形变 (　　)