—____________ difficulty you meet, remember that it might just be a touchstone.

—You are right. __________ difficult it is, we will never give in.

A．However; whatever

B．However; however

C．Whatever; whatever

D．Whatever; however

在甲、乙两烧杯中分别加入含等物质的量的硫酸溶液，再向甲烧杯中加入m g镁，向乙烧杯中加入m g锌。完全反应后，有一烧杯中仍有金属未溶解，则每一烧杯中反应前H₂SO₄的物质的量x的值是…(    )

A．<x<

B．x≥

C．>x≥

D．x≤