如图，在平行四边形ABCD中，∠C=120°，AD=2AB=4，点H、G分别是边AD、BC上的动点．连接AH、HG，点E为AH的中点，点F为GH的中点，连接EF．则EF的最大值与最小值的差为（   ）

口语交际。

根据课文内容，发挥你的想象，请为青海湖风景区拟写一段导游词。

读短文并按要求完成相应任务
    Today was the first day of the summer holiday．My friends and I went out together．We went swimming in the swimming pool．We swam for an hour．I did not swim well，but I enjoyed it very much．We had lunch in a fast—food restaurant．I had a sandwich and some orange juice．Alice had a hamburger．Jack had a lot of French fries and some cola．We went shopping in a supermarket．I bought a pink dress．Alice bought a pretty hat．Jack did not buy anything．
    We went home at 3 o'clock in the afternoon．We 、were tired，but we were happy．

下列二次根式中,是同类二次根式的是(     )

读拼音，写词语。 

①yōu ____闲 ____美  ____虑

②mào ____失    草____    ____盛