______ difficult it is, he is determined to ______ the experiment.

A．No matter how; have a go at

B．However; have a go for

C．Whatever ; have a go

D．No matter what; have a go at

城市由于建筑密集，生产与生活活动散发大量热量，往往出现市区气温比郊外高的现象，这被称为( )。

A．温差效应

B．绿岛效应

C．温压效应

D．热岛效应