A：到原来的2倍
B：到原来的4倍
C：到原来的6倍
D：到原来的8倍
The famous piano teacher ______ Robby as a student only because he said it had always been his mother's dream to hear him play the piano.
如果让你探究“种子的萌发需要水分吗？”，你选定的变量是（ ）
单词拼写。
清政府特许的统一经济管理贸易机构是（ ）
