A：细菌病毒
B：植物病毒
C：动物病毒
D：细菌
下列句中加线词的意思和用法与例句相同的一项是（ ）。
例句：货恶其弃于地也。
— There's somebody at the door. Who ____ it be? Is it the postman?—No. It ______ be him. It's just seven o'clock. It's too early.
下列能构成生态系统的是（ ）
