①属于不文明行为        ②是不道德行为，但不违法

③属于违法行为            ④应受刑罚处罚

滑动摩擦力的大小跟____ 和____ 有关．压力的作用效果跟____ 和____ 有关，压力的方向总是____ ，重力的方向总是____ ．

如图所示的区域内有垂直于纸面的匀强磁场，磁感应强度为B．电阻为R，半径为L，圆心角为45°的扇形闭合导线框绕垂直于纸面的O轴以角速度ω匀速转动（O轴位于磁场边界）．则线框内产生的感应电流的有效值为（   ）

    If(如果) you don't like reading books, this is for you.

    Have a few laughs (笑声). Sit down with a book of jokes, a picture book or a funny story- book first.

    Ask around. Ask your friends or your teachers about interesting books.

    Find new interests. After reading, you may find an interest in something new.

    Go to the library. Don't be shy (害羞) about asking a librarian (图书管理员) a question like, “Do you have any books about soccer?”

    See the world (世界). When you want to know or see something, you can open the book about it.

    Try to read, you can find there is a lot of fun in books.