下图是北半球亚热带某地降水量逐月累计曲线图，读图，该地水循环最活跃的季节是(    )

从方框中选出合适的词补全文章

    BBC is one of the most famous radio____  in the world．It has its own offices in London and in many other parts of the country，even in the____  countries． 

    People can find out all the BBC programmes in the BBC'S magazine Radio Times．The magazine has much more readers than any

____ magazine in Britain．BBC has a lot of radio channels(频道)and TV channels．There are all kinds of____ on them．Some are for parents，and some are for____ ．Some are for workers and farmers，and some are for teachers and students．Some give main news and some give music or sports．You can choose what you like to listen to or to watch

下列结论：

⑴ac＜0；

⑵当x＞1时，y的值随x值的增大而减小．

⑶3是方程ax²+（b﹣1）x+c=0的一个根；

⑷当﹣1＜x＜3时，ax²+（b﹣1）x+c＞0．

其中正确的个数为（   ）

2014年吉林省对全省供热管网进行改造，改造后全年二氧化碳排放量共减少7620000吨，7620000这个数用科学记数法表示为（  ）