—I will come back in eighteen days.
A：How often
B：How long
C：How soon
D：How much
— Jenny, I think I'll just have some coffee for a change．
— ______．The coffee I bought yesterday is in the cupboard．
——I can hardly believe my eyes. Is that you, Lucy?——Yes. It has been almost 20 years______ we were together.
下列成语中，哪个说明了生物能够影响环境的道理（ ）
