A、the optical unit must be positioned so that the sun does not shine into the aperture.光学设备必须被定位以便使太阳照进光圈

B、there is are latively high rate of false accepts.有一个相对较高的错误接受率。

C、the iris pattern changes as a person grows older.虹膜图案随着一个人年龄的增长而变化。

D、concern that the laser beam may cause eye damage.关注激光束可能会导致眼睛损伤。