根据对话内容判断下列句子正误。

John：What did you do last Saturday，Mike?

Mike：On Saturday I went to the zoo．

John：Did you go there by yourself?

Mike：No．I went there with my brother．

John：What about Sunday?

Mike：I helped my mum with the housework．

John：Did you wash the clothes?

Mike：Yes．Also l cleaned the window and cooked with my mum．What about your weekend?

John：Nothing special．I just was at home and did my homework on Saturday．and I visited my grandparents on Sunday．

如图甲所示是呼气式酒精测试仪的电路原理图，R为气敏电阻，它的阻值随酒精气体浓度的变化曲线如图乙，R₀为定值电阻，电源电压保持不变.检测时，驾驶员呼出的酒精气体浓度越大，则

最小的两位数与最大的一位数之和是(      )。

如图，AC与BD相交于点O，若OA=OB，∠A=60°，且AB∥CD，求证：△OCD是等边三角形．

下边各组句子中多义词的意思不正确的一项是（    ）。