早期先天梅毒是指发病年龄（）
A.小于2岁
B.小于1岁
C.大于2岁
D.大于5岁
E.小于4岁
参考答案：A
As we have known from the map of the world，this is ________.
A．twice as large an island as that
B．twice as larger as that island
C．as twice large as that one
D．twice as a large island as that
物体距凸透镜20cm时，可在光屏上得到一个缩小的实像，若把物体向透镜方向移8cm，又可在光屏上得到一个放大的实像，则透镜的焦距是（ ）
A．20cm
B．10cm
C．9cm
D．5cm
