题目

A special lady lived on a farm in Grace, Idaho. To overcome every  41  or struggle that came her way, she went far beyond the call of duty. She was a widow (寡妇) with 9 children. Instead of  42  of her hard life, she accepted her fate (命运) and  43  the ordinary into the extraordinary. No matter how serious things seemed to be, she found a(n)  44  side and a ray of hope. She taught her family the  45  of hard work and the importance of education,  46  she only went as far as fourth grade.  Her children didn’t have material  47 , but they certainly received the Ti质粒上有T-DNA,这种DNA可以转移到受体细胞,并且整合到受体细胞染色体的DNA上。这种质粒存在于 A．大肠杆菌       B．农杆菌         C．酵母菌        D．苏云金芽孢杆菌