A:2—乙基丁烷
B:2,4—二甲基戊烷
C:1,3,4—三甲基己烷
D:2,4,4—三甲基戊烷
The computer system________suddenly while he was searching for information on the Internet.
I don't think looking after(照看)children is just work.
下列实例中,与食物链有关的是( )