Leaders of many countries have been trying to _____ what itis that makes China develop so fast in recent years

What should parents do when their children have someproblems? –I think it’s ____ for them to be therewith their children.

This is ____ book I bought yesterday. Isn’t it _____useful one

依次填入下列各句横线处的成语，最恰当的一组是①细心的观众可能会发现，第四局的时候王励勤不时口中 ，不知道在说些什么。王励勤自己在赛后揭开了这一谜底：“我在鼓励自己，还有提醒自己一些技术要领。”②谢某直到被抓，口中仍然 。据了解，谢某系辽宁大连人，60岁，在7个月时间里，只和家里联系了2次。今年3月，心存侥幸的他第二次来到江阴，终于落入法网。③讲台上朴实无华的周晓路研究员 ，时而用生动形象的比喻解释着复杂难懂的概念和术语，时而用简单明了的例子来说明SCI文章创作的思维方式。

The classroom is big enough for 25 studentsfor normal use you needmore space for special activities