应选
The manager said that there were two reasons _____ our sales dropped sharply last year.
The manager said that there were two reasons \_\_\_\__ our sales dropped sharply last year.
某酯水解生成甲和乙两种物质，在同温同压下，相同质量的甲和乙的蒸气占有相同的体积，则该酯的结构简式为（ ）．
某酯水解生成甲和乙两种物质，在同温同压下，相同质量的甲和乙的蒸气占有相同的体积，则该酯的结构简式为（ ）．