关于外毒素
A．性质稳定，耐热B．毒性较强C．无抗原性D．主要由革兰阴性菌产生，少数革兰阳性菌也司产生E．以上均对
参考答案：B
My daughter likes to have her photos taken _____ there are many different kinds of flowers. [ ]
A. there
B. in which
C. when
D. where
新疆绿洲的特色农产品是（ ）
A．棉花、甘蔗和多种瓜果
B．棉花、甜菜和多种瓜果
C．棉花、花生和多种瓜果
D．棉花、葡萄和西瓜
