引起缺铁性贫血的主要原因是
A．慢性失血B．妇女妊娠或哺乳C．青少年生长发育D．食物中供铁不足E．胃大部切除术
参考答案：A
方程x2﹣3x+2=0的根是 ．
Many teachers __________ to the meeting are from Chongqing.
A．invited
B．to invite
C．be invited
D．had been invited
