两个作用在一条直线上的力F₁、F₂。当F₁=18牛、F₂=8牛，它们的合力是 （）

我国面积最大的省级行政区是（   ）

   Now many students have become crazy about c ____  cards in my school. Some have been collecting them ____ about three years. After one gets card, he will____ (分享)it with his friends. Many students are so addicted (上了瘾的) to it that they have changed a lot. Some students even play with the cards in class. So they have fallen behind in their____ .
   The card is i ____  as a gift in the bag of some food. T ____ , to get these cards, many students try their best to ask for ____  from their parents. I hear Tim and Tom have already collected more than one t____  cards from stores or their friends.  ____  is not long for them to collect a lot of cards. But without good care, the cards can be taken away easily by other collectors. So many students fight with each other for the cards.
   I suggest that as a student, we shouldn’t be too fascinated(感到，着迷的) in collecting cards ____  longer. Study hard and become a good host of the future!