根据《森林法》第四条，我国森林可分为（）、（）、（）、薪炭林、特种用途林这五大类。
参考答案：防护林；用材林；经济林
根据句意及首字母完成单词。
1. R _____ to call me as soon as you get to Shanghai.
2. U_____, by the time I got there, the bus had already left.
3. I've never been late for school, but yesterday I came very c _____.
4. I'll never forget what you t _____ me.
5. On Saturday I was e _____ because last Friday night my friend and I stayed up really late.
为什么要将芯片进行封装？封装后的器件比裸芯在性能上有什么不同？
