在等式y=kx+b中，当x=-1时，y=0；当x=0时，y=-1．则这个等式是（

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问题选择题

在等式y=kx+b中，当x=-1时，y=0；当x=0时，y=-1．则这个等式是（　　）

A．y=-x-1

B．y=-x+1

C．y=x-1

D．y=x+1

答案

把x=-1时，y=0，当x=0时，y=-1，

代入y=kx+b得到方程组

-k+b=0

b=-1

，

解得

k=-1

b=-1

．

则这个等式是y=-x-1．

故选A．

选择题

读一读句子，看一看小朋友们描述的是哪样食品，选择正确的图片。

( ) 1. Amy: I like it. It's yellow. It's very long.

( ) 2. John: I like to drink it. It's yummy. It's from the cow.

( ) 3. Sarah: It's big and round. The color is green.

( ) 4. Mike: I like it. It's red. It keeps the doctor away.

( ) 5. Liu Yun: It's not big. It's very small. It's purple.

单项选择题

颗粒剂干燥失重按药典法测定，除另有规定外，不得超过

A．0.5%
B．1.0%
C．1.5%
D．2.0%
E．8%