简述“针孔成像”原理。
参考答案：
It was ________ he came back from Africa that year ________ he met the girl he would like to marry.[ ]
A．when; then
B．not; until
C．not until; that
D．only; when
新生儿坏死性小肠结肠炎出现哪项应考虑外科治疗（）
A.呕吐胆汁
B.发热不退
C.便血
D.腹胀
E.大量气腹
