Why do many people keep dogs as pets—Because they are our ____ friends and theynever desert their masters

He ate a lot and did little exercise, so he _______ 10 pounds.

One of the most important problems we willhave to solve is ____of students’ learning method

依次填入下列各句横线处的成语，最恰当的一组是(　　)①当执法人员对假冒少数民族的小贩进行处罚时，该小贩故作听不懂。执法人员拟对物品暂扣时，他又原形毕露，________，强词夺理，企图不接受处罚。②英国统治阶层普遍缺乏科学知识，对数字毫不敏感，只会靠________治理国家。③中共十八大在京召开，让记者们眼前一亮的是，此届党代表没有了以往的“沉默是金”，取而代之的是________，直抒胸臆，畅所欲言。

. —When did your school hold the sports meet—Last week. And I _______ the girls’ 400-metre race.