装置如图，通电后，发现Cu极附近溶液蓝色加深。下列说法正确的是

A．A极为负极，Cu为阳极

B．左烧杯溶液和右烧杯溶液pH都变小

C．左烧杯Pt极和右烧杯Fe极的电解产物物质的量之比为1∶1

D．左烧杯溶液浓度变大，右烧杯溶液浓度不变

An increasing number of students,year by year,across China  _______ hard to realize their dream of studying abroad.

A．try

B．have tried　

C．will try

D．are trying