When I first lived abroad, I had to do the housework for others____a week’s accommodation.

A．in exchange for

B．with regard to

C．by means of

D．in place of

引起细菌性食物中毒的最常见致病菌是（）

A.沙门菌

B.葡萄球菌

C.变形杆菌

D.副溶血性弧菌

E.致病性大肠杆菌