题目

阅读短文，根据其内容回答文后各个小题． Using iPads to Make Learning Fun Paper，pencil，whiteboard，textbook are the tools you need if you want to go to school．But recently，you can add another one to the list：an iPad． Because the popular Apple tablet is not only useful for searching the Internet and watching videos，but it is also being used to make learning fun． Scientists now know that we learn better when we are enjoying ourselves，so recently software developers have made iPad applications（应用程序） that look like video games，but have strong一氧化氮是汽车尾气中的一种大气污染物，它是无色气体，难溶于水、密度比空气略大，在空气中能与氧气迅速反应生成红棕色的二氧化氮．在实验室制取一氧化氮时，收集一氧化氮应采用的收集方法是（ ）A．向上排空气集所法B．排水集气法C．向下排空气集气法D．排水集气法或向上排空气集气法