入射光线与镜面的夹角是20°，则入射角是　 ____　度，入射光线与反射光线的夹角是　 ____　度，如果入射光线垂直射到镜面上，那么反射角是　 ____　度．

如图甲所示，用铁架台、弹簧和多个已知质量且质量相等的钩码探究在弹性限度内弹簧弹力与弹簧伸长量的关系．

请仔细阅读下列各小题，从A.B.C.D中找出其相对应的选项。

    You don't have to be bored on a rainy day. Here are some new ideas:

    Tell stories. You might tell stories you have heard before, or you might make up some wonderful stories.

    ①___________. You can learn to cook a pizza or maybe some cookies. Give your friend a chance to help in the kitchen and make something tasty.

    ②___________. You might write stories on your own and then read them aloud to others, or you might write a story together.

    ③____________. Think of some scenes and then play a game. Act as teachers, doctors, nurses or policemen. You can dress up in whatever you may have.

    ④____________. Pick out some music and dance around in the room. You can also sing while others are dancing.

So on the next rainy day, try some of these ideas for a day full of fun!