焦化厂所用配煤罐的数量一般比配煤所用煤种的数量多2-3个，其主要作用是在（）、煤罐不下煤时备用。
参考答案：更换配比
根据括号中所给的汉语写出单词，使句子意思完整正确。
1. Mr. Dong, have you learnt a lot about the city's past and _________ (现在)?
2. The whole area is _________ (控制) by our army.
3. The Eiffel Tower was _________ (设计) by Gustavo Eiffel.
4. We were _________ (鼓掌) our hands while the performers were marching across the park.
5. Although there was strong wind, the plane arrived the airport _________ (安全).
食品标签要注意哪6大要素？
