－6+0－10=____

小波在阅读历史文献时发现，很多国家在古代常用文字中有关“马”的词汇特别多；而现代常用文字中关于“马”的词汇少了很多，但关于“机”的词汇却多了。造成这种变化的根本原因是（   ）

阅读下面这首唐诗，完成后面小题。

咏怀古迹（其五）

杜甫

诸葛大名垂宇宙，宗臣遗像肃清高。

三分割据纡筹策①，万古云霄一羽毛。

伯仲之间见伊吕，指挥若定失萧曹。

运移汉祚②终难复，志决身歼军务劳。

【注解】①纡筹策：曲折周密地展运策略。纡yū：弯曲，屈。②祚（zuò）：帝位。

在水平桌面M上放置一块正方形薄木板abcd，在木板的正中点放置一个质量为m的木块，如图所示．先以木板的ad边为轴，将木板向上缓慢转动，使木板的ab边与桌面的夹角为θ；再接着以木板的ab边为轴，将木板向上缓慢转动，使木板的ad边与桌面的夹角也为θ（ab边与桌面的夹角θ不变）．在转动过程中木块在木板上没有滑动，则转动之后木块受到的摩擦力大小为（   ）

根据短文内容，回答问题。

Pisces (February 20 to March 20)

      It's the sign of the fish. Pisceans are very free-flowing（自由散漫的）people. They often feel bad when they cannot do the things that they want to. When things don't run well, they will often become very angry. A Piscean can usually make the best of a bad situation if they really want to. They can easily get along with other people and the outside world.

      Quality: Negative（阴性）          Ruler: Neptune （海王星）

      Triplicity: Mutable （变通型）     Quadruplicity: Water （水相）

      Pisces can be given cameras, socks and shoes as presents. Music of all kinds is welcome, such as CDs, piano and concert tickets. Anything that makes a Pisces think of water and seas is great, such as ships, going boating, a trip to the sea and a hot bath.