地衣能从岩石中获取营养,分泌的地衣酸会腐蚀风化岩石,这说明生物与环境的关系是[ ]
A.相互适应
B.相互影响
C.生物依赖环境,又影响环境
D.生物既适应环境,又影响环境
D
—Jim, do you have a PC?
—Yes, I _____ it for almost a year. [ ]
A. have bought
B. has bought
C. have had
D. has had
电子数据交换的国际标准是()。
A、美国国家标准局(ANSI)主持制定的X.12数据通信标准
B、EDIFACT数据通信标准
C、ANSIX.12和EDIFACT两个标准
D、以上三种说法都不正确