已知倾斜角为θ的直线，与直线x﹣3y+1=0垂直，则tanθ=（　　）

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!

已知在酸性溶液中，下列物质氧化KI时，自身发生如下变化：Fe³⁺→Fe²⁺；MnO₄^﹣→Mn²⁺；Cl₂→2Cl^﹣；HNO₃→NO．如果分别用等物质的量的这些物质氧化足量的KI，得到I₂最少的是（　　）