孕妇容易发生高危妊娠的年龄（）
A.<18岁
B.<18岁或>35岁
C.>35岁
D.<19岁或>35岁
E.<19岁或>36岁
参考答案：B
分解因式：x2-4x+3=______．
— Has your mother finished her paper yet?
— I don’t know; she _______ it this morning.
A．wrote
B．has written
C．had written
D．was writing
