I usually use my computer _________my emails and buy tickets.

A．check

B．chceks

C．to check

D．checking

增值税一般纳税人销售免税货物，一律不得开具专用发票(国有粮食购销企业销售免税粮食除外)。如违反规定开具专用发票的，则对其开具的销售额依照增值税适用税率全额征收增值税，并不得抵扣进项税额。( )