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．

如图所示是利用胚胎工程技术培育优质奶牛的主要步骤。下列叙述正确的是( 　　)

下图示意河套平原地区。当地将黄河水通过引水渠引入区内灌溉农田，农田灌溉退水经过排水渠汇入乌梁素海。近年来乌梁素海出现污染加重趋势。