根据汉语意思完成英文句子。 1. 微波炉可以用来煮饭。 A microwave oven can _____ _____ _____ cooking. 2. 你必须亲自去签收,他们不能邮寄过来就算。 You have to go sign for it _____ _____, they can't just mail it. 3. 人类怎么会说这么多种语言,这种情况是如何产生的呢? How did it _____ _____ that humans speak so many different languages? 4. 老师告诉我们噪音对我们的耳朵伤害很大。 The teacher told us that noise _____ very _____ _____ our ears. 5. 在每一项发明被发明出来之前,爱迪生总要做大量的实验。 Before each invention was invented, Thomas Edison always did _____ _____ _____ _____.