______ makes the school proud is_______ most students have been admitted by the key universities.

____ by taking part in practice can the young people be toughened and hardened into steel

For a moment nothing happened .Then ____ of the falling stones and soils.

Sandy, do you ________ tomorrow’s party— Yes. Everything is OK.

填入下面一段文字横线处的语句，最恰当的一句是(　　)专家表示，汞经常出现在我们的日常生活中，如果对含汞产品使用或处理不当很容易造成汞污染。________________，达到一定量便会对人体产生危害，严重的甚至会造成汞中毒。因此，建议定期进行汞含量检测，并掌握与汞相关的科学知识，做好汞污染的预防工作。