——Would you like to come to my house for dinner tonight?——I'd love to , _____ I have lots of work to do .
A:so
B:or
C:and
D:but
(2015·四川)将苏云金杆菌Bt蛋白的基因导入棉花细胞中,可获得抗棉铃虫的转基因棉,其过程如下图所示(注:农杆菌中Ti质拉上只有T-DNA片段能转移到植物细胞中)。