A：I can’t find him anywhere
B：By searching the whole building
C：He’s all right, as long as you do what he say
D：I haven’t seen him for long, he is very busy these day
若方程ax2+bx+c=0（a≠0）满足a+b+c=0，则方程必有一根为（ ）
30. We want to make a fruit salad. We need __________ ice cream.
关于我国自然灾害特点叙述错误的是（ ）
