A:阶级性
B:革命性
C:科学性
D:实践性
下列污染物中,通过食物链危害人体的是( )
—Sorry, it's too difficult for me and I can't manage to do it.
已知x=5-12,则x2+x+1= ____
选择句子补全对话。
A. Is it green? B. What do you see? C. What colouris it? D. Good morning, Alice.
Danny: ____
Alice: Good morning, Danny.
Alice: I see a bird.
Alice: No, it isn't.
Alice: It's red.