有下列函数：
①y=x2-3|x|+2；
②y=x2，x∈（-2，2]；
③y=x3；
④y=x-1，
其中是偶函数的有（ ）
A．①
B．①③
C．①②
D．②④
①f（-x）=（-x）2-3|-x|+2=f（x），为偶函数
②定义域（-2，2]关于原点不对称，非奇非偶函数
③f（-x）=（-x）3=-x3，为奇函数
④f（-x）=-x-1≠f（x）≠-f（x），非奇非偶函数
故选 A
| 阅读短文，回答问题。 | |
He puts on his new white T-shirt and yellow cap. He says goodbye to his parents and goes to the bus stop. The bus stop is near his home. He is going to meet his classmates there. The zoo is very far but a No. 1 bus will take them right there. The children are going to see many animals in the zoo and they are going to have a good time. 1. What day is it today? _________________________________________________ 2. Where are the children going? _________________________________________________ 3. What are they going to see? _________________________________________________ 4. Are they happy? _________________________________________________ 5. Is Mike wearing a yellow T-shirt? _________________________________________________ |