A:can manage
B:could have managed
C:could manage
D:can have managed
Our English teacher is very kind ________us.
— Neither. I like cartoons because they often make me laugh.
在一个生态系统中,已知初级消费者与次级消费者的个体数分别为N1和N2,个体平均重量分别为M1和M2,则下列四项中正确的是( )