原油中的钠主要影响催化剂的水热稳定性和酸性,而造成活性下降。
参考答案:对
Because of the Russian gas limit to Europe, attempts _______ to use botanical fuel as a source of power.
A.have made
B.having made
C.are being made
D.will be making
级机关转发本机关的文件(包括报纸,刊物转载),在归档范围中属()材料。
A.归档;
B.参考;
C.不归档。