-- The math problem _________ is not difficult.

--- But after several tries , I have to give up _________ on it .

A．it’s , working

B．itself , to work

C．itself , working

D．its , to work

易被椰毒假单胞菌污染的食物是（）。

A.剩饭、凉糕、奶及奶制品

B.家庭自制豆制品、罐头食品、腊肉

C.鱼、虾、蟹、贝类

D.臭米面、变质银耳、糯米汤圆粉、淀粉制品

E.肉类、禽类和蛋类